Bacteria are complex compared to viruses. In addition, it may have extra loose bits of DNA called plasmids floating in the cytoplasm. Some have threadlike structures called flagella that they use to move. A virus may or may not have an outermost spiky layer called the envelope. And that's it.
Viruses are moochers.
They contain only a limited genetic blueprint and they don't have the necessary building tools. They have to invade other cells and hijack their cellular machinery to reproduce. Viruses invade by attaching to a cell and injecting their genes or by being swallowed up by the cell. Here's an example of viral infection. This is virus version of the horror movie Alien .