My understanding:
There are only two types of fuel in SC: Quantum and "normal"
Quantum you can run out of and must purchase. Starfarers refine quantum.
Regular you can run out of. But you can refill it on your own with fuel scoops. As such, you'll never be completely stranded but you might have to limp to a station very slowly.
AB simply injects normal fuel into the engine to produce more thrust for faster acceleration. After you hit max speed (this replaces cruise mode) you no longer accelerate. But you continue to burn fuel as your engine idles. Once your scoops refill your fuel enough, you can AB again. However, after hitting max speed, you'll eventually slow down (space friction?) and need to AB again to get back up to max speed.
There isn't a separate "afterburner fuel"....
Again, just my understanding (and I could be wrong). I can't wait to try it.