How can I differentiate prokatyotic and eukaryotic cells?

The main difference between these two cell types is that eukaryotic cells have their DNA collected inside the nucleus, while prokaryotic cells lack nuclei. Instead, they have a circular piece of DNA called the nucleoid anywhere in the cytoplasm, and other smaller, ring-shaped DNA pieces called plasmids.There are, of course, many other ways to tell them apart. For example, the organelles they contain (prokaryotes lack many organelles that are normal in eukaryotes, like the endoplasmic reticulum, mitochondria or the Golgi apparatus), or their level of organisation (prokaryotes are unicellular organisms, like bacteria; whereas eukaryotes can organise into multicellular living beings, like plants, fungi or us!).