What is the difference between a gynecology doctor and an obstetrics and gynecology?

Women's Health: Obstetrics deals with safe delivery of an infant at the completion of a pregnancy. The obstetrician has to view the mother as 2 patients because there is a baby and a mother to watch. Gynecology is the care of women specific health problems usually related to the vagina, uterus, and ovaries. The basic training is similar for both fields so they are often linked together and practiced together.

One sleeps more...: A gynecologist is trained but no longer chooses to do obstetrics, therefore no prenatal care, middle of the night deliveries, or c-sections. They concentrate on gyn surgeries, health care maintenance, and basically everything but pregnancy.

Birth: Initially they are trained in both specialties, an ob/gyn practices obstetrics and gynecology. A "gynecologist" practices only gynecology.