AIDS stands for Acquired Immune Deficiency Syndrome. Acquired means that you get it or obtain it, rather than inheriting it from your parents' genes. A baby can be born with AIDS, but that is because the mother's body fluids mix with the baby's body fluids while she is pregnant. Immune deficiency means that some part of the immune system is damaged so that it can no longer work right.
Syndrome is another word for an illness or a group of symptoms.
HIV stands for Human Immunodeficiency Virus. This virus lives in blood and body fluids. It attacks the immune system, so that a person with HIV cannot fight off diseases as well as a healthy person. AIDS is the most serious illness that occurs in people who have been infected with the HIV virus. The most common diseases that strike people with HIV are called opportunistic infections .