What's the difference between viruses and bacteria?

Bacteria are actually living, single-celled organisms whereas viruses are not actually alive in the same way bacteria are. Scientists still debate whether or not viruses should be considered living or just organic structures. Viruses hijack the cells of their host and cause them to make copies of the virus, eventually destroying the host cell. This is why bacteria can be killed with antibiotics, whereas viruses must be vaccinated against, where the body is trained to identify and remove the virus.