Final answer:
Prokaryotic cells are characterized by the absence of a nucleus, while eukaryotic cells have a membrane-bound nucleus.
Step-by-step explanation:
Cells fall into one of two broad categories: prokaryotic and eukaryotic. Animals cells, plant cells, fungal cells, and protist cells are classified as eukaryotic, whereas bacteria and archaea cells are classified as prokaryotic. Prokaryotic cells are characterized by the absence of a nucleus, while eukaryotic cells have a membrane-bound nucleus.