Where do you draw the line?

So I have been seeing and reading stuff about so many wars that happened in the 20th century. I like that history is getting all the more fascinating for me. I have wondered whether studying history has any value at all. Surely we don't learn from our mistakes and we always find avenues to make similar (though outwardly new) mistakes. But that's perhaps a wrong way to look at it. Utility is perhaps overrated.
History is simply fascinating because there are just so many stories in there. And we will never get to know what truly was! Half-possibly wrong- knowledge is exciting. It sometimes drives me nuts.
Yeah, as I was seeing all these war stories, this question came to me. I know this is talked about and all that. But I had never considered it seriously enough. The question is about drawing a line between a terrorist and a freedom fighter. Anyone who makes use of violence to induce terror can be called a terrorist, right? Now if he is fighting to separate a particular group from some other group can he be called more of a freedom fighter and less of a terrorist? A freedom fighter can be a terrorist. He would be a terrorist freedom fighter. Just because he is fighting for freedom (so-called freedom. I totally think freedom is a misnomer, though I don't have competitive alternatives at the moment) he won't stop being a terrorist. But my question is, when does he start becoming a freedom fighter? After a certain number of people start supporting his cause? (Who decides this number anyway) Isn't the title 'freedom fighter' more because of a result that follows? That is, if he is successful in pursuing his cause, then he gets called a fighter for freedom. But if he failed, he would still remain a terrorist? So, does success alone bring validity to the cause? Perhaps I'm being biased about the 'label' of a 'freedom fighter' as something good. But that is indeed the general opinion, right? Freedom fighters are respected. They are seen as heroes. As people who stood for a greater cause. But terrorists are bad examples, they are detested and feared.
So, yeah, when does a revolt(an act of terrorism) become a struggle for freedom? Is it when there are a lot people who support it? Or when there are people who are already successful vouch for it? Or if it happens for a long period of time and causes substantial loss and thereby prove that it's with a consistent reason?
I wonder if rationality is perhaps somewhere in the bottom of the list of reasons for something to be seen as 'right' and 'good'.