What's the difference between viruses and bacteria?

Bacteria are living cells with their own metabolism, they can reproduce on their own and many are harmless, whereas viruses are just genetic code wrapped in proteins that need to get into your cells to duplicate themselves. That's why antibiotics kill bacteria but not viruses - they destroy cellular structures that viruses don't have.

What really sets the two apart is that viruses need you to exist. A bacterium is a complete organism that can live anywhere - in soil, in water, even in your fridge. A virus is just a piece of genetic code that can't do anything on its own. It has to get into one of your cells to reproduce, otherwise it just stays inactive.

So antibiotics kill bacteria by attacking their cellular structure, but they don't work on viruses at all. That's why when you catch the flu, your doctor won't prescribe you antibiotics - it would be pointless. You have to let your immune system handle it for a few days.

For example, I had a throat infection last year and I was convinced it was viral, but the test ended up showing it was a streptococcus bacterium. Ten days of antibiotics and it was cleared up. If it had been a virus, I would've just had to wait for it to go away. It's proof that these two really don't work the same way at all.