Hey OP.
They updated a lot of the mounts to have unique running animations and unique mount specials (pressing spacebar while idle).
The Infernals are no longer remodeled gronnlings, the fox runs different with a new animation. The felbats are remodeled gronnlings but with a modified run animation and flight animation. The rat mount no longer looks like a hideous tailless bear - it has a unique animation. The fish is completely new, the spider is completely new. The Storm dragons are scaled way bigger than regular drake mounts.
This is a good expansion for mounts.
WoD was the worst expansion for mounts ever. But they did have to create over 25 new skeletons in higher detail than normal with a ton of animations.