Recently I had bought SpaceChem and upon completing all the research challenges, I was able to craft 2 items in TF2 and one of them was the Fishcake. The stats of the Fishcake are identical to the Dalokohs Bar, so is there a difference in what this 2 items can do?
No, the Fishcake is simply a reskinned version of the Dalokohs Bar. Both items have the same stats and behave the same way, the only difference is visual. TF2 has quite a few such items, the official wiki has a list.