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.
The differences between a column and a pillar are the same as the differences between a pillar and a column, which I pointed out here: answer to What's the difference between a pillar and a column? gv