<human>:  What is the difference between a bacteria and a virus?
<bot>: The main difference between a bacteria and a virus is that bacteria are much larger and are single-celled organisms, while viruses are much smaller and are not considered to be living organisms. Bacteria can reproduce on their own, while viruses need to invade other cells in order to replicate. Bacteria can be destroyed by antibiotics, while viruses are unaffected by antibiotics. Bacteria can cause illnesses, while most viruses cause infections.