What are some of the major differences between viruses and bacteria?

Viruses are parasitic organisms that cannot survive outside a living host. They are considered to be non-living, however this still remains debatable amongst virologists. They infect their host and utilise its proteins and machinery for their own replication, spread and survival. Viruses typically consist of a specific type of genetic material, DNA or RNA, surrounded by a protein coat, the capsid, and on some occasions have an extra envelop of lipids surrounding the protein coat. Viruses are in their majority very small, much smaller than bacteria (with the exception of giant viruses that have comparable sizes to bacteria), and can infect all types of organisms, including bacteria.

Bacteria, on the other hand, are living, prokaryotic (i.e. unicellular) organisms made up of DNA. They were one of the first life forms to inhabit Earth and, therefore, can survive on their own in a number of different conditions and environments. However, on occasions, they form symbiotic or even parasitic relationships with other organisms. Antibiotics are only effective against bacteria and not viruses.