There are four main factions shown in TFA:

**The New Republic** - formed from what was the Rebel Alliance, since they are no longer rebelling, they have won.
>! The planet that gets destroyed by Starkiller base is the New Republic's current senate headquarters (the senate rotates planets, like the Olympics)
    

**The Empire** - still controls some systems, but is at peace with the Republic now and has been supposedly de-militarized. (not directly shown in the movie)

**The First Order** - formed from remnants of the Empire who didn't want to give up fighting, they operate illegally from the shadows.

**The Resistance** - Princess Leia left the Republic to fight the First Order, but officially doesn't have Republic support (unofficially is perhaps a different matter).

*(Source: Star Wars: The Force Awakens Visual Dictionary)*