A psychiatrist is an MD who can write perscriptions for medications, while a psychologist cannot. Yes, that is true, but the other differences are more slight.. The psychiatric philosophy tends to view mental illness as neurochemical imbalances, and as more of a medical condition to be treated. most psychiatrists do not perform cognitive therapy or behavioral modification therapy or any kind of 'talk' therapy at all. They see you, they treat you, you go on your way.. A psychologist is more interested in why you are ill, not just how. What factors in your life influenced the negative thought patterns, what interventions can be performed to give you insight into your behavior and instill coping mechanisms to deal with it in the future. usually, in psychologists work with psychiatrists, as a team, to optimize the chances of reaching an effective cure or control of your mental illness