Is there a difference between the pets?

[slogsdon]

Or is it just looks?

[jamesL]

in their initial form there is no difference
the only differences show up when you feed them different fish

[RizzRustbolt]

Falcor is about 20% more handsome than the other pets.

[slogsdon]

in their initial form there is no difference
the only differences show up when you feed them different fish

So they react differently to fish?

[Steffe]

in their initial form there is no difference
the only differences show up when you feed them different fish

So they react differently to fish?

Think he meant that they gain different skills/abilities depending on the fish, they all transform to the same animal though.
For instance a Muckfish will transform your pet, no matter what it is, into a Jackalbeast.

There's even ones that transform your pet into another permanently (until another fish is eaten). Hopefully there will be a way of transforming them back to their original form in the full game.