My hubs is a DO. He went to a DO med school, DO surgery residency, MD family practice residency, took the same tests for board certification as MDs, taught at an MD medical school, was the Chief of Department in Family Practice at a huge teaching hospital, etc, etc.There are DO and MD residencies, and a DO is qualified to apply for an MD residency.

The difference is that DOs have additional training during medical school in "osteopathic manipulation" which is similar to what a chiropractor would do. Usually you'll only find this done by a family practice doc or orthopedist. DOs are not necessarily more "holistic" apart from that.

My hubs now practices a new specialty in medicine called Hospitalist. He takes care of people referred to him by other doctors, including psychiatrists (for medical issues, not psych issues), only while they are in the hospital. He requests the consultations with other doctors. On discharge, the patient is transferred back to their original doctor. This system means there is ultimately one doctor coordinating care. You have one doctor who can explain why the others are seeing you. It is an exploding field because people want to have a go-to doctor who can "put together the big picture". Just giving out that information because people always ask, "What is a Hospitalist?" and you might see one if, God forbid, you or a family member is hospitalized.

Hospitalists can be DO or MD, as well.