What is the difference between bacteria and virus?

Both bacteria and viruses are too small to be seen with the naked eye. One of the most important differences between bacteria and viruses are the methods they use to survive and reproduce. Bacteria are single-celled organisms with DNA, ribosomes, cytoplasm, cell wall and cell membrane. On the other hand, viruses need a living cell to survive. This cell is called a host cell. The structure of all viruses includes DNA or RNA, which allows them to grow and maintain their vital activities, in the host cell, as well as a protein sheath that protects them, called capsids.