Both psychiatry and psychology come from the Greek word, "Psyche", which means "Soul". In modern society, the word, "Psyche" means mind, or use of the mind. Even though psychiatry requires a medical degree, and psychology does not, they are almost identical because they deal with behavior, mental health and counseling.
Webster's dictionary describes behavior in the psychological sense as , "The actions or reactions of persons or things in response to external or internal stimuli.", or in a more simple form ; The way in which one behaves. In both fields, and working with patients with behavior issues, both psychiatrists, and psychologists, work in very similar ways. They both provide the same type of treatment, by using verbal communication, in trying to figure out the problem. They ask the same questions, give the same suggestions, and so on. The difference is, is that psychiatrist do a little more detailed research on the subject, and or patient.
Mental Health is also a large role in both psychiatry, and psychology. The main difference, is that mental health can be more serious when dealing with a psychiatrist. Mental illness is described as , The psychological state of someone who has emotional or behavioral problems , serious enough to require medical intervention. Mental illness is a term used in psychiatry and psychology, in only severe cases.