Not Protein, Protean.
I was being facetious.
Those are not different types of armor, but the same kind of armor for different types of agents (or soldiers). Due to the way that OXC handles unit properties, some attributes are assigned to units themselves, while others are part of the armor definitions.
Ah, that would explain it, then. Thank you. However, it still doesn't make sense to me that a suit of armour should be heavier and bulkier (but offering the same protection), just by adding night vision goggles. Wouldn't it make more sense for it just to have the combined drawbacks as the armoured vest and the NightOps armour? Ie., -5, -5 and -10 to TU, stamina and reactions respectively.
Although I have to say, stamina has never been remotely an issue for me in Xcom-Files, not even with rookies.