The Abbasid Caliphate differed from others in that it did not have the same borders and extent as Islam. Particularly, in the west of the Caliphate, there were multiple smaller caliphates that existed in relative peace with them.
The major difference between the protist and the animal kingdom is protists are unicellular protozoans and unicellular & multicellular, but animals are multicellular animals.
Key difference: The main difference between USA and Canada is in their government. USA is a federal constitutional republic, whereas Canada is a constitutional monarchy. Further differences include geographic and climate. Canada also differs in its stance against some political and cultural aspects.