In which of these are archaea and bacteria significantly different? cell size chromosome size and organization lack of a membrane-enclosed nucleus membrane lipid structure possessesion of membrane enclosed organelles?

Archaea and bacteria both have procaryotic cells, therefore they lack organelles enclosed by a lipid membrane like the ones found in eukaryotes  ( nucleus, the mitochondria, Golgi apparatus etc.) 
They are very similar when it comes to chromosome size and organization, both having circular chromosomes, unlike the linear chromosomes that eukaryotes have.
One of the many distinct differences between these two group of organisms is the structure and the composition of the bilayer lipid cell membrane.
The archaea have ether lipids in their membranes, as opposed to bacteria whose membrane have ester lipids. 

C- a hypothesis or d- an observation