One of the other large differences is that in coop mode, you start the next level in exactly the same state as you ended the previous level: heath, ammo, and carried equipment. Even if the game engine makes you restart the map, you restart it with whatever you had when you started it.

Versus mode won't be able to do that, it has to start each side with a fresh slate every map, or it would be unfair.

This means that one of the unique aspects of coop mode is that you don't want to use your equipment if possible so you can save it for later. However in Versus since your just playing a single map, you want to use everything you have. This would mean you're going to use different tactics on each map, which then makes them play differently in the different modes.