The key difference between prokaryotic and eukaryotic cells is: Prokaryotes lack membrane-bound organelles, while eukaryotes have them.
To clarify the other statements:
- Prokaryotes do not have a nucleus; instead, their genetic material is not enclosed within a membrane, while eukaryotes do have a nucleus.
- Eukaryotes are generally larger than prokaryotes.
- Both prokaryotes and eukaryotes can have ribosomes, and while many eukaryotic cells have a cell wall (such as plants and fungi), not all eukaryotes do, and many prokaryotes also possess a cell wall.