The most obvious difference between prokaryotic and eukaryotic cells is the presence of a nucleus.

* Eukaryotic cells have a true nucleus enclosed by a membrane, which houses their DNA.

* Prokaryotic cells lack a nucleus and their DNA is located in a region called the nucleoid, which is not enclosed by a membrane.

This difference in DNA organization is fundamental and leads to many other differences in the structure and function of these two cell types.