[*NOTE*]: The examples I'm giving are for the NATO vests. [*NOTE*]
There should be more model differences for each of the different NATO vests. Not only would it be nice eye-candy, but it could help distinguish between soldiers.
The "Lite" and "Rig" ones should stay the same, however, the GL version should have pouches with grenades in them (like the OPFOR LBV GL harness), and possibly neck and groin protection. The Special Rig vest should have less pouches and some other details.