The major and extremely significant difference between prokaryotes and eukaryotes is that eukaryotes have a nucleus and membrane-bound organelles, while prokaryotes do not. The DNA of prokaryotes floats freely around the cell; the DNA of eukaryotes is held within its nucleus.

Prokaryotes have a cell wall composed of peptidoglycan, a single large polymer of amino acids and sugars. Many types of eukaryotic cells (e.g. Plants) also have cell walls, but none made of peptidoglycan. many Bacteria have external structures called Pili that they use to attach to other cells.

Some similarities between the two types of cells (prokaryotic and eukaryotic) are: They both have DNA as their genetic material. They both have Plasma membranes. They both have ribosomes to make proteins.

Classifying bacteria on the basis of their morphology is extremely difficult; bacteria are generally quite small and have simple shapes. In addition to shape, bacteria have traditionally been identified and classified on the basis of their biochemistry and the conditions under which they grow.