As in does the Comp 4 have a different mount than the Comp 2, etc. Thanks

They are modular.  The bases are all the same, but depending on what you buy, i.e. PRO, M3, M4, etc you will get different parts to complete the mount.

The base, spacer, ring, and cantilever extension can all be assembled as necessary.  There are two different bases, the thumb nut, and screw head type.

Aimpoint designed a pretty neat system that works well.  If you look on their site you will find many different parts that can be combined to make all sorts
of combinations.

Thanks, everything I needed to know.