Recently I've been re-watching SG1 and noticed that the characters mostly wear the green BDUs, but occasionally wear the blue BDUs (I'm not referring to the blue jumpsuit they sometimes wear, mainly on ships). I was wondering; was there ever a reason given as to why they would wear the different colours? I know it can't have anything to do with rank, position or specialty since the same people would wear different colours. Also, it wouldn't seem to be for camouflage purposes (really, blue doesn't blend into anything very well).