Core Differences: Viruses vs. Bacteria
The main difference is that bacteria are living, single-celled organisms, while viruses are non-living infectious agents. Bacteria can reproduce on their own, have their own cellular machinery, and are much larger. Viruses are much smaller and must infect a living host cell to replicate.
Structure and Treatment
Bacteria have a cell wall, cell membrane, cytoplasm, and genetic material. They can be killed by antibiotics, which target these structures. Viruses are simpler, consisting only of genetic material (DNA or RNA) inside a protein coat. Because they are not living cells, antibiotics are ineffective against them; instead, they are fought with antiviral medications and vaccines.