As far as helmet designs perhaps, but in Halo 4, you can mix and match shoulders, helmets, chest pieces, forearms, and legs, and you can have armor skins for each piece as well whihc is pretty cool. So that seems like a lot of variety and customization to me...
There is no Forest armor, it is the Forest skin for the Hazop armor.
You do have to complete the game on legendary to get Mark VI which is techically MC's armor lol