I would think it's a combination of both.
It's kinda like a controlled instability.
You can actually hear a change in motor speeds if you hover close
to you & work the controls one direction at a time.
For example,in order to go forward,similar to tilting the
rotor forward on a heli, the rear motors speed-up and/or the
forward motors slow down.
Thus tilting the nose down & raising the rear..enabling forward motion.