What’s an easy way to tell the difference between a eukaryote and prokaryote

Prokaryotes are organisms made up of cells that lack a cell nucleus or any membrane-encased organelles. Eukaryotes are organisms made up of cells that possess a membrane-bound nucleus that holds genetic material as well as membrane-bound organelles

Nucleus

Explanation:

I used to remember the difference between eukaryote and prokaryote by the nucleus. Eukaryote cells have a nucleus while prokaryote do not. Hope this helps