Here's why:

* Prokaryotic cells are simpler and lack a true nucleus and other membrane-bound organelles. Their DNA is located in a region called the nucleoid, which is not enclosed by a membrane.

* Eukaryotic cells have a well-defined nucleus that houses their DNA, as well as other organelles like mitochondria, Golgi apparatus, endoplasmic reticulum, lysosomes, and more. These organelles are all enclosed within membranes, which allows them to carry out specialized functions within the cell.

So, the key difference is the presence of internal membranes that create compartments for specialized functions in eukaryotic cells.