Eukaryotic cells are larger and more complex than prokaryotic cells, containing membrane-bound organelles. Prokaryotic cells like bacteria are simpler and smaller, lacking organelles. Organelles such as the nucleus, mitochondria, chloroplasts, and endoplasmic reticulum allow eukaryotic cells to perform specialized functions. Eukaryotic cells evolved from prokaryotic cells through endosymbiotic relationships where prokaryotes living inside host cells became permanent resident organelles.