270oUt, let's start at the purest:
Back-full (mobius loop) - there a completely vertical backflip (360°) plus a full twist (360°) = 720°. You end up back on your feet facing the same direction. The twist usually doesn't start until half way through the flip in order to maintain the integrity of the flip.
D-spin 7 - the backflip does not go completely vertical because the twist is started earlier than in a back-full (you can see this by the third frame of Jon's sequence). Historical note: Mike D's anxiety when learning the back-full on the water ramp caused him start the twist early, hence a new trick was born.
Because the flip is not perfectly vertical, it is less than 360°, but I still need to end up back on my feet facing the same direction (720°). More twist gets added automatically (a biomechanical phenomenon known as tilt twisting). For argument's sake, let's just say the backflip component comprises 270°, then 450° needs to be made up by the twist.
Corked 7 - The backflip NEVER gets past horizontal (<180°). The rest is all twist (>540°). Since the twist is the key here, starting it very early and aggressively will ensure the flip doesn't really materialize.
If there's interest, I can add a trampoline video in the summer section demonstrating these 3 in order.