What is the difference between an MD physician and an osteopathic physician?

Honestly, not much any more. Both Doctors of Osteopathic Medicine (D.O.)/osteopathic physicians and Doctors of Medicine (M.D.) attend medical school for four years, sit for licensure examinations, go to residency to specialize in any field of medicine, get board-certified, perhaps attend fellowship, etc. Both can prescribe medications, perform surgery, work in a hospital or academic setting, and so on. There is a slight difference in training during medical school-during the four years of osteopathic medical school, in addition to learning the traditional medical curriculum that DOs and MDs learn (anatomy, biochemistry, histology, pathology, etc.), DO students also receive 300-500 hours of instruction in a form of manual therapy known as osteopathic manipulative treatment (OMT).