Here's a breakdown:
* Eukaryotic cells have a nucleus enclosed by a membrane, containing their DNA. They also have other membrane-bound organelles like mitochondria, endoplasmic reticulum, Golgi apparatus, etc.
* Prokaryotic cells lack a true nucleus. Their DNA is located in a region called the nucleoid, which is not enclosed by a membrane. They also lack other membrane-bound organelles.
So, the presence of a true nucleus is the defining characteristic that distinguishes eukaryotic cells from prokaryotic cells.
