We have bacteria and archae. Eukaryotes are animals, plants, protests and fungi. Now, prokaryotes do not have a nucleus. In fact, they do not have any membrane bound organelle whatsoever. However, eukaryotes do have a nucleus, and they do contain membrane bound organelles, such as the mitochondria or the endoplasmic reticulum. Now, prokaryotes are mostly unicellular, but some multicellular prokaryotes do in fact exist, while eukaryotes come in both types, we have unicellular and multicellular eukaryotes, as we'll see in a future lecture.