Bacteria are small or tiny cells, which can be seen with a microscope. They live in wet and moist environments in the body and grow quickly and causes infection. The infection caused by a bacteria can be treated with an antibiotic.
Viruses are smaller than bacteria with respect to size and they cannot be seen with the help of a microscope. They also grow in a body like bacteria and generates certain toxins and poisons which causes rashes, fever, etc. They cannot be treated with antibiotics likewise bacteria.