A doctor of medicine, or MD, consists of four years of medical school in which students take classes in microbiology, pharmacology and physiology. MedlinePlus Medical Encyclopedia says the main functions of an MD include the diagnosing, treatment, correction, advisement or prescription of disease, injury, deformity pain and physical and mental problems. They treat both adults and children. Medical doctors work in private practice, group medical facilities, public health organizations and emergency rooms. They need three to eight years of clinical or hospital residencies before taking board and state licensing exams.
A doctor of osteopathic medicine, or DO, receives the same medical training as an MD in addition to osteopathic manipulative medical techniques. According to the Cleveland Clinic website, osteopathic manipulation is the use of techniques meant to treat the whole body by applying pressure to points on the body, specifically in the lower back and neck. They primarily work with patients suffering from sports injuries, stress injuries and headaches. To earn this degree, students must complete a 12-month internship and enter a two- to six-year residency before taking board and state licensing exams.
A doctor of internal medicine, or internist, diagnoses and treats adult diseases. Internists may work as primary care specialists or work in specialized fields. According to the American College of Physicians, internal medicine consists of 13 subcategories: cardiology, geriatrics, adolescent medicine, endocrinology, infectious disease, oncology, pulmonology, rheumatology, allergy and immunology, gastroenterology, hematology, nephrology and sports medicine. They often consult with physicians to diagnose mystery illnesses. Internists must complete three to seven years of medical school and post graduate training before receiving their board certification and taking the state exam.
Pediatric medicine teaches students to care for the physical, mental and emotional health of children from infancy to age 18. They provide preventative health care, as well as care for children suffering from chronic ailments and infectious disease. According to the University of Maryland Medical Center, pediatricians may choose specialties in behavioral difficulties, developmental disorders, depressions, genetic problems, cancer and organ disease and dysfunctions. Pediatricians work in private practice, health clinics and hospitals. After medical students finish medical school, they must complete three to eight years of internships and residency programs.