What is the difference between IVF and IUI?

IUI (Intrauterine Insemination): Specially prepared sperm are placed directly into the uterus around the time of ovulation. Fertilization happens inside the body.
IVF (In Vitro Fertilization): Eggs are retrieved from the ovaries and fertilized by sperm outside the body, in a lab. The resulting embryo is then transferred into the uterus.