Twice, Max calls Dr. Hammer a psychiatrist, and twice someone corrects him: Hammer is a psychologist.In the U.S., licensed psychologists hold a doctorate in their field, while licensed psychiatrists hold a medical degree with a specialty in psychiatry. Psychiatrists are physicians who have earned an M.D. or a D.O. professional degree, whereas psychologists have earned a doctor's degree Ph.D., Psy.D., or Ed.D. The Ph.D. is the highest required doctoral degree awarded by universities. The term "Doctor" means "Teacher of Teachers" or "Learned Professional." Psychiatrists generally spend shorter periods of contact time with clients/patients, and the principal method of treatment is psychopharmacology.
--Wikipedia