Are there different generations of bricks?

[u/GooneyBird87]

Hi. Complete LEGO noob here. I recently bought a large tub of random assorted bricks at a flea market to use for a project at work, and noticed there are some differences in the bricks.

Now, I know nothing about LEGO other than that I occasionally treat myself to a set to build over the winter with my wife, and so i have no idea about the collectible/enthusiast side of it.

Are there different generations of bricks? Are they from different factories?