Question

Compare provirus and retrovirus.

Answer 1

Retrovirus can become provirus
A provirus is already in the DNA host cell , whereas retrovirus exists outside of a cell.

Answer 2

cmkc 109 is right that a provirus is a DNA sequence which has been integrated into the host cell genome. In contrast, a retrovirus is a complex of protein and RNA in which there is a packaged RNA genome. Transcription from the provirus results in RNA genomes and the gag, pol and env proteins necessary for the retroviral life cycle. The fact that the RNA genome gets changed into the DNA provirus is the reason that these viruses are known as retroviruses - the transcription is in the opposite way from normal. The normal transcription is from DNA to mRNA.