Talion has 4 classes for each of the alliances, each of which is named differently than in a regular RPG, but at the same time performs the same functions. The classes are the same for both alliances (the only difference is in the name):
Kyle (warrior) - a strong fighter who has good health and protection, and can be a team tank.
Velletrin (assassin) Is a fast assassin who lurks in the shadows and relies on high damage per second and critical attacks.
Pell (mage) - Deals magic damage, and has skills that deal damage over time and have a very large radius of action.
Aizen (shooter) - possesses a variety of weapons, from swords to bombs and magic guns. His skills are very slightly different from other classes.
Choose a class according to your playstyle - no matter the choice, you can't go wrong anyway, because they are all powerful.