AIDS stands for:
In short, over a period of time the body's immune system breaks down, and the person is unable to fight off infections and other certain diseases. AIDS is caused by an infection with the HIV virus.
HIV stands for:
HIV is a virus that enters a person's bloodstream. At first, and usually for a very long time afterward, there are no signs or symptoms that indicate that the person has been infected. Make no mistake about it, the person is infected and is infectious (able to spread it to others).
A lot of people think that HIV and AIDS are the same thing; but they're not. An HIV diagnosis means that the person is infected with the HIV virus. They can be infected for a very long time before they begin to have health problems. In the later stages of infection, when the immune system has fallen to a particular level or the person has been diagnosed with certain diseases, the diagnosis changes to AIDS.