* You call them “terrorists” when their cause is one you don’t believe in.
* You call them “freedom fighters” when their cause is one you DO believe in.
* And you call them “guerrillas” when you aren’t sure.
An ongoing, classic example is the conflict in Chechyna. In the American media, the soldiers there tend to be called “guerrillas” or “rebels”. Never “freedom fighters”, and I haven’t yet heard them called “terrorists”. I think we just don’t know what to make of them. The Russians, on the other hand, refer to them quite clearly as “terrorists”.
It looks like a bunch of them seized a school down in Georgia (Russia, not U.S.) and the news stories about the situation refer to them as “guerrillas”. Still not sure, I guess. It seems to me that grabbing a school and holding a bunch of kids hostage isn’t a “freedom fighter” kind of thing to do…