Well, simply put, friendly villages would be open - you could just walk in and look through their ammo crates, use their MASH tent, whatever.
if we could set it up right, you would be able to talk to certain civvies who would tell you what they knew about enemy movement and positions.
Hostile villages would either shoot at you right away or call for backup, so you wouldn't be able to take anything unless you killed everybody.
Neutral villages just wouldn't have anything worth taking - that's the simplest way to distinguish, I think.