Followings are the key differences
1. Viruses are the smallest and simplest life form in general 10 to 100 times smaller than bacteria.
2. Bacteria are single-celled organisms that can live either inside or outside other cells. They can survive without a cellular host. Viruses, on the other hand, are only intracellular organisms, meaning that they infiltrate the host cell and live inside the cell. Viruses change the host cell's genetic material from its normal function to producing the virus itself.
3. Bacteria have all the "machinery" (cell organelles) needed for their growth and multiplication and usually reproduce asexually.
4. By contrast, viruses generally carry information - for example, DNA or RNA, packaged in a protein and/or membranous coat. They need the host cell's machinery to reproduce.
5. Antibiotics cannot kill viruses, but can kill bacteria case to case basis.