Collision hull and mesh understanding

Hello, I’m just a little bit confused and would like someone to validate what I believe or correct me if im wrong.

So from my understanding a collision hull is a simple box around the actual collision mesh that tells the source engine when two things are close enough to start processing collisions using the collision mesh?

It seems like the player entity (the actual player) only use a collision hull? But for a ragdoll the collision mesh is used, but how does the collision hull work for that … does it constantly resize to the “volume” depending on how its bent?

I think a collision hull and a collision mesh are the same thing :v: -wikipedia seems to think so