Both MDs and NDs are trained in a 4-year graduate-level program. MDs' training focuses on a mechanistic way of viewing the human body (like separate physical parts), whereas ND's focus on looking at the body as an integrated whole (like a physical body, emotions, and a spirit, all in the context of heredity and environment)
Both MDs and NDs must take licensing exams. ND's licensure rules vary by state. Both use similar diagnostics.
MDs utilize therapeutics based on their mechanistic view of the body, so they use pharmaceuticals and surgery as well as many higher technological approaches. ND's utilize therapeutics based on their holistic and individualized perspective and use a variety of natural approaches, including herbs, homeopathy, nutrition, and nutritional supplementation, among others. ND's also focus on preventive care.