Gringots has 4 degrees of motion (pitch, yaw, roll, and movement along the track). From the prototype that I saw, it appears that Guardians will only have 2 degrees of motion (yaw and movement along the track). With Gringots, the movement along the track is minimal and relatively slow and the primary storytelling device (with regards to the ride vehicle) is in the movement of the vehicles in the pitch, yaw, and roll dimensions. With Guardians, the movement along the track will be much more significant with the yaw rotation just pointing you in specific directions during specific portions of the ride. I like to think that Guardians is more of a dark ride with some roller coaster like elements while Guardians will be a roller coaster with some dark ride elements.
(Disclaimer... I know nothing about the ride itself and all of the above is just educated guesses based upon what we do know).