Before the patch i thought my eyes were tricking me, there were different colored goblins, but i didn't think twice about it because i was so busy beating the cr@p out of it.
It wasn't until 1.08 when they started announcing "player has engaged Scoundrel , treasure pigmy, treaser seeker" that there are indeed different types by name and color. Some seem to run faster too.
So thinking back I'm assuming the different types has a higher chance of dropping certain things
I have remember some goblins dropping in one go 4-5 gems
or another dropping piles of gold than items
another dropping alot of tome of secrets / blue items
and the usual one is just a random mix so do the different types have a high chance of dropping certain rare loot (excluding legendaries of course).
I noticed the ones summoned by puzzle ring are always scoundrel at lv 61?