What is the difference between HIV and other viruses?

HIV (Human Immunodeficiency Virus) belongs to a group of viruses called retroviruses. While it is not the only member of this group, it is by far the most well known. Normal viruses consist of a DNA strand in a protein shell. When these viruses infect a living cell, they transcript their DNA into RNA and integrate said RNA into the host cell. The affected cell then produces more viruses, killing itself in the process. Retroviruses, however, contain not DNA but RNA in them. When a retrovirus infects a cell, it turns its RNA into DNA with the help of an enzyme called reverse transcriptase. This means that instead of RNA, a retrovirus injects its DNA into the host cell. Later, the host cell, as in case of normal virus infection, produces more viruses. But in addition to this, cells with viral DNA can divide and create more infected cells before the viral DNA becomes active. However, the most dangerous quality of HIV and other retroviruses is that reverse transcriptase's transcription of DNA is terribly inaccurate. This leads to many random errors in the viral DNA and, therefore, to multiple random mutations in the virus strands. Even the viruses inside one single man can differ wildly in their genetic code. Most scientists agree that, at the moment, it is almost impossible to find an effective drug against HIV due to these random mutations and to such significant differences between all of them.