Prokaryotes are simpler, older types of cells. They do not have a true nucleus — instead, their genetic material (DNA) floats freely in the cytoplasm in a region called the nucleoid. They also lack membrane-bound organelles like mitochondria or the endoplasmic reticulum. Prokaryotic cells are generally smaller in size and are mostly unicellular organisms, like bacteria and archaea. Their DNA is circular, and they reproduce mainly by binary fission. Many prokaryotes have a cell wall made of a substance called peptidoglycan. Their ribosomes are smaller compared to eukaryotic ribosomes.

Eukaryotes, on the other hand, have a well-defined nucleus enclosed by a nuclear membrane. They possess various membrane-bound organelles such as mitochondria, endoplasmic reticulum, Golgi bodies, and lysosomes, which carry out specialized functions. Eukaryotic cells are usually larger and are often part of multicellular organisms, such as animals, plants, fungi, and protists. Their DNA is linear and organized into chromosomes. Eukaryotic cells divide by mitosis or meiosis. They may or may not have a cell wall — plants have one made of cellulose, fungi have one made of chitin, but animal cells do not have a cell wall. Their ribosomes are larger than those in prokaryotes.