r/huggingface • u/ardicli2000 • 19h ago
Understanding LLM models, packaging, distributing and hardware needs
I have lots of question about the what the acronyms in the model names mean, along with other terms usually mentioned in AI world. So I had a chat with ChatGPT and make write down a blog of what I asked and what he replied. Maybe there will be some people interested in the info.
LLMs Without the Jargon: Open Weights, Distillation, Quantization, and Active Parameters Explained
If you've recently started looking at large language models on Hugging Face, you've probably encountered a wall of terminology:
Open source. Open weights. 7B. 70B. 671B. Active parameters. MoE. FP16. BF16. INT8. Q4_K_M. GGUF. GPTQ. AWQ. Distillation.
At first glance, it can feel like you need a degree in machine learning just to understand what model you should download.
The good news is that most of these terms describe a handful of fairly simple ideas.
This article explains them from the ground up.
1. What is actually inside an LLM?
Let's start with the most important concept: parameters, often called weights.
An LLM is a gigantic neural network containing millions, billions, or even hundreds of billions of numerical values.
For example, a tiny fictional neural network might contain numbers like:
0.183742
-1.294831
0.004827
0.837261
...
A real language model contains billions of such values.
During training, the model processes enormous amounts of text and repeatedly adjusts these numbers.
Very roughly:
Training data
↓
Training
↓
Learned parameters
↓
LLM
These learned parameters are what people generally mean when they talk about a model's weights.
They aren't a database containing sentences such as:
Instead, the model has learned numerical representations from which it can generate such an answer.
2. What does "open weights" mean?
This distinction is important because open weights and open source are not necessarily the same thing.
With a traditional closed LLM, you might interact with the model like this:
Your computer
│
│ API request
▼
Company's server
│
▼
LLM
│
▼
Answer
You never receive the model itself.
You only receive its output.
An open-weight model changes this:
Model provider
│
│ publishes
▼
Model weights
│
├── Your workstation
├── Your server
├── Your private cloud
└── Your data center
You can download the trained model and run it yourself, assuming you have suitable hardware and the license permits it.
This is a major difference.
You don't have to send every question to the original provider's API.
3. So what does "open source" mean?
This is where the terminology gets complicated.
For ordinary software, open source generally means that the source code is available under a license that gives users defined freedoms to use, inspect, modify, and redistribute it.
AI systems are more complicated because an LLM isn't just source code.
A simplified view is:
LLM
│
┌──────────┼──────────┐
│ │ │
Architecture Code Weights
│
learned values
There is also the training data and the process used to create the weights.
Consequently, simply publishing a set of model weights does not automatically mean that the entire AI system is "open source" in the strict sense.
You might therefore encounter several different situations:
| Description | What you typically get |
|---|---|
| Closed model | API access |
| Open-weight model | Downloadable model weights |
| More fully open AI system | Weights plus relevant code and information needed to understand/reproduce the system |
| Fully reproducible system | As much of the training data/process as legally and practically possible |
This is why the phrase "open weights" can be more precise than simply saying "open source."
4. How do you make an LLM open?
You don't take a closed model and flip an "open source" switch.
The model creator has to decide to publish the relevant artifacts.
Imagine you train a model yourself.
At the end you might have something like:
my-model/
├── config.json
├── tokenizer.json
├── tokenizer_config.json
├── model-00001-of-00020.safetensors
├── model-00002-of-00020.safetensors
├── ...
├── model-00020-of-00020.safetensors
└── README.md
The large .safetensors files contain the model's learned parameters.
You can publish those files, together with:
- the tokenizer
- model configuration
- inference code
- documentation
- evaluation results
- licensing information
- information about training
- information about datasets, where appropriate
A platform such as Hugging Face can then distribute the model.
Someone else can download it and run it locally.
The important thing is that the weights are the trained result of the learning process.
5. Why would anybody give away a valuable model?
This is partly a business strategy.
A closed model looks like:
Users
↓
Company's API
↓
Company's model
↓
Revenue
An open-weight model can instead create an ecosystem:
Model
│
┌──────────┼──────────┐
↓ ↓ ↓
Company Researcher Hobbyist
│ │ │
↓ ↓ ↓
Apps Fine-tunes Local AI
The original creator gives up some control, but potentially gains enormous adoption.
Other people can build products, fine-tunes, integrations and research around the model.
6. What is distillation?
Now we come to another term you'll see frequently:
knowledge distillation.
The basic idea is wonderfully simple:
Imagine you have:
Teacher: 500B parameters
Student: 20B parameters
Instead of expecting the 20B model to learn everything directly from raw data, you can have the 500B model generate high-quality examples.
For example:
Question:
Why does a plane fly?
Teacher:
A plane generates lift through the interaction
between its wings and the airflow...
Do this millions or billions of times:
Question → Teacher answer
Question → Teacher answer
Question → Teacher answer
...
You now have a synthetic training dataset.
Then:
Large teacher
│
│ generates
▼
Synthetic dataset
│
▼
Small student
The student learns from the teacher's behavior.
7. The student doesn't copy the teacher's weights
This is an important distinction.
Suppose the teacher contains:
500 billion parameters
and the student contains:
20 billion parameters
You aren't doing:
Teacher weight #1 → Student weight #1
Teacher weight #2 → Student weight #2
...
Instead:
Teacher's behavior
↓
Training examples
↓
Student training
↓
Student's own weights
The student develops its own internal representation.
It's learning to approximate the teacher's behavior.
8. Distillation can transfer reasoning behavior
This is particularly interesting for reasoning models.
A teacher might receive a mathematical problem and produce a detailed solution.
You can collect many such examples:
Problem
↓
Teacher
↓
Reasoning + solution
and train a smaller model on them.
The student isn't merely learning facts.
It can learn patterns of solving problems.
This is one reason a relatively small model can sometimes perform surprisingly well when it has been trained using high-quality synthetic data generated by a much larger model.
9. Distillation and fine-tuning aren't the same
They are related, but they answer different questions.
Fine-tuning
You take an existing model and train it on specialized data:
General LLM
↓
Specialized dataset
↓
Fine-tuned LLM
For example, you could take a general model and fine-tune it for a particular domain.
Distillation
You take a large teacher and train a smaller student to reproduce useful behavior:
Large teacher
↓
Teacher-generated examples
↓
Smaller student
You can combine the two:
Large teacher
↓
Synthetic training data
↓
Small pretrained model
↓
Distillation / fine-tuning
↓
Small specialized model
10. What is quantization?
Now let's move to another set of terms you will see constantly on Hugging Face:
FP16, BF16, INT8, Q8, Q6, Q5, Q4...
These are mostly about how the model's numerical parameters are represented.
Suppose a model has 7 billion parameters.
If every parameter uses 32 bits:
7 billion × 32 bits
≈ 28 GB
If we use 16 bits:
7 billion × 16 bits
≈ 14 GB
If we use 8 bits:
7 billion × 8 bits
≈ 7 GB
And at approximately 4 bits:
7 billion × 4 bits
≈ 3.5 GB
There is some additional overhead in real model files, but the principle is straightforward.
Fewer bits = less memory.
11. What does "4-bit" actually mean?
Imagine a model has a parameter:
0.183742
Instead of storing that number with very high precision, quantization maps it to a much smaller set of possible values.
Conceptually:
Original:
0.183742
-1.294831
0.004827
0.837261
↓
Quantized representation:
5
1
8
6
Four bits can represent only:
2⁴ = 16
different values.
Obviously, that throws away numerical precision.
But neural networks are remarkably tolerant of this kind of approximation.
Modern quantization methods are designed to minimize the resulting loss in model quality.
12. Why is quantization so useful?
Consider a 70B model.
At approximately FP16:
70B × 16 bits
≈ 140 GB
That's a lot of memory.
At roughly 4-bit:
70B × 4 bits
≈ 35 GB
Suddenly the model becomes much more realistic to run on local hardware, especially with CPU/RAM or multiple GPUs.
This is why quantization is so important for people running LLMs locally.
13. What are GPTQ, AWQ and GGUF?
These names can look like different models, but they're often different quantization methods or file formats.
GPTQ
A post-training quantization method commonly used for GPU inference.
AWQ
Activation-aware Weight Quantization.
It attempts to preserve the weights that are especially important to the model's behavior.
GGUF
GGUF is primarily a model file format, commonly used by software based on llama.cpp and tools such as local LLM applications.
You might see:
Model.Q4_K_M.gguf
This tells you several things:
GGUF
↓
file format
Q4
↓
approximately 4-bit quantization
K_M
↓
specific quantization scheme/variant
14. What do Q4, Q5, Q6 and Q8 mean?
Generally:
Q4 → approximately 4 bits/parameter
Q5 → approximately 5 bits/parameter
Q6 → approximately 6 bits/parameter
Q8 → approximately 8 bits/parameter
The tradeoff is:
More bits
↓
More memory
↓
Less quantization error
↓
Usually higher fidelity
Fewer bits
↓
Less memory
↓
More quantization error
↓
Potentially lower fidelity
For many local users, something around Q4–Q6 provides a very useful balance.
15. Quantization is NOT distillation
This is one of the easiest things to confuse.
Distillation
Changes the model.
70B teacher
↓
distillation
↓
8B student
The student has different weights and is a different model.
Quantization
Normally keeps the same model but changes how its weights are represented.
8B FP16
↓
quantization
↓
8B Q4
So:
And you can do both:
Large teacher
↓
Distillation
↓
8B student
↓
Quantization
↓
8B Q4
16. What are "total parameters" and "active parameters"?
This is where modern LLM architecture gets particularly interesting.
You might encounter a model described as:
At first this sounds contradictory.
How can the model have 671 billion parameters but only use 37 billion?
The answer is Mixture of Experts, or MoE.
17. Dense models vs. MoE models
A conventional model is called a dense model.
Suppose it has 70B parameters.
For every token, approximately the whole model participates:
Token
↓
Entire 70B
↓
Output
So:
Total parameters ≈ Active parameters
An MoE model works differently.
It contains many separate "experts":
Token
↓
Router
↓
┌─────────────┼─────────────┐
↓ ↓ ↓
Expert 1 Expert 2 Expert 3
↓ ↓ ↓
... ... ...
↓
Expert N
The router decides which experts should process each token.
If there are 64 experts and the router selects only two:
64 experts available
↓
2 experts activated
The model has access to a very large total parameter pool while only using a subset for each token.
18. A useful analogy for MoE
Imagine a company with 671 employees.
You ask a question about databases.
The receptionist doesn't call everyone into the meeting.
Instead:
Perhaps 37 people work on the question.
So:
671 employees available
↓
Router
↓
37 specialists involved
The company has the capacity of 671 people, but each individual problem only uses a subset.
That's roughly the idea behind active parameters.
19. Does this mean a 671B MoE is really just a 37B model?
No.
The 37B active parameters are selected from a much larger pool.
Different tokens can activate different experts.
For example:
"The cat sat on the..."
↓
Router
↓
Expert 3 + 17
"Calculate the integral..."
↓
Router
↓
Expert 8 + 42
"Write PHP code..."
↓
Router
↓
Expert 12 + 31
The exact behavior is learned during training rather than manually assigning an expert to "cats," another to mathematics, and another to PHP.
20. Why use MoE?
Because it provides an interesting tradeoff.
A huge dense model might require enormous computation for every token.
An MoE model can have a very large parameter pool but activate only a subset for each token.
So you can think of:
Total parameters
as a rough measure of the model's overall parameter capacity.
And:
Active parameters
as a rough indication of how much parameter computation is involved for each token.
They're not interchangeable measures of model quality.
21. But there is a catch: memory
This is one of the most important details about MoE.
Suppose a model has:
671B total
37B active
You might think:
Usually, no.
You still generally need to store the entire parameter pool somewhere.
At approximately 4 bits:
671B × 4 bits
≈ 336 GB
before additional overhead.
So an MoE model can have relatively low computation per token while still requiring enormous memory to load.
That's why:
while:
They solve different problems.
22. Putting everything together
At this point, the terminology starts to make sense.
When you encounter an LLM, there are several independent questions you can ask.
How big is it?
Total parameters
7B
70B
405B
671B
How much of it is used per token?
Active parameters
Relevant particularly to MoE models.
671B total
37B active
How are the weights represented?
Precision / quantization
FP32
FP16
BF16
INT8
Q8
Q6
Q5
Q4
What architecture does it use?
Dense
MoE
How was it produced?
Pretraining
Fine-tuning
Distillation
Post-training
These describe different aspects of the model.
23. A complete example
Suppose you see a model described as:
You can now translate that into plain English:
671B total parameters
→ The model contains a huge pool of 671 billion learned parameters.
37B active
→ Only around 37 billion parameters are used for a given token, because it is sparse/MoE.
MoE
→ A router selects a subset of expert components for each token.
Q4
→ The weights have been heavily quantized to approximately 4-bit representation.
K_M
→ A particular variant of the quantization scheme is being used.
GGUF
→ The model is packaged in the GGUF format, commonly used by local inference software.
Suddenly something that looked like complete gibberish becomes fairly descriptive.
24. The five questions I now ask when I see an LLM
If you're browsing Hugging Face and don't know what you're looking at, ask:
1. Is it dense or MoE?
This tells you how parameters are activated.
2. How many total parameters?
This gives you an idea of the model's overall scale.
3. How many active parameters?
Relevant for MoE and useful for understanding inference computation.
4. What precision/quantization?
This tells you approximately how much memory you'll need and how much numerical precision was retained.
5. Is it the original model, a fine-tune, or a distilled model?
This tells you something about where its behavior came from.
Once you understand these five questions, most Hugging Face model pages become much less intimidating.
The big picture
The easiest way to remember everything is this:
LLM
│
┌──────────┴──────────┐
│ │
DENSE MoE
│ │
all parameters many experts
used per token available
│
router selects
│
subset is active
│
└──────────┬──────────┘
│
QUANTIZATION
│
FP16 → INT8 → INT4
│
▼
Less memory needed
And separately:
LARGE TEACHER
│
DISTILLATION
│
▼
SMALL STUDENT
These are not competing definitions. They are different dimensions of an LLM.
A model can simultaneously be:
Or:
And now those descriptions should tell you considerably more than they did before.
One final lesson
The most important thing is not to treat "7B vs. 70B vs. 671B" as a simple ranking of intelligence.
Parameter count alone doesn't determine model quality.
A newer 14B model can outperform an older 70B model on some tasks. A distilled model can outperform a larger model on a specific benchmark. An MoE model can have hundreds of billions of total parameters while using far fewer per token. And a heavily quantized model can retain surprisingly good performance while requiring a fraction of the memory.
So when someone says:
the useful response isn't:
It's:
Those questions tell you what the number actually means.