They are similar, but not the same. They have different connotations depending on how they are used.
A rebel is a person who is refusing to submit in one way or another to a certain power. A revolutionary is someone that, while they may refuse a power, have a desire to change the power and make it something new or base it on a new concept, something, and please ignore the pun, revolutionary. In the example that this author used it is correct, and, in fact, is a good question to ask. Is the character simply not willing to submit themselves? Or are they trying to change the world?
Both, actually. The aim is to stop the rebels and save the world from destruction by Pokemon. And @dudebot, I know I made quite a bit of mistakes. XP The general thing is though that I don't really explain the plot or characters that much until later in the story. And yeah, there are still humans around, but mostly their hiding out in cities, because I'd sure as hell hide if a dragon was patrolling around cracking off Dragon Rage every few steps. X3