I believe the Ravager has the ability to track enemies somewhat and features an explosive projectile that the Burst Carbine does not.
I'll check, update in minute.
Update: The Ravager seems to have a slower firing speed, combined with a slower projectile that explodes on impact dealing a small amount of AOE damage. It also looks like it has to been manually vented or it overheats. The Pulse Carbine shoots fast and seems to cool on its own, but also has a manual vent option if the heat meter goes to high. It's also pretty accurate.