What is the difference between the Psychologist and the Psychiatrist?

As a psychologist practicing psychotherapy, I have often been asked the question of what is the difference between psychology and psychiatry or of the psychologist and the psychiatrist.

The answer basically revolves around the difference between the mind and the brain. The psychologist's core training revolves around the mind (psyche) and the psychiatrist around the brain (soma). First, the two are not the same. And whereas the psychiatrist tends, given his core medical training, to retrieve mental phenomena to brain processes, we now -with the advent of a more profound understanding of consciousness- can say brain processes result from the mind.

The following quote of Freud sheds some light on this question:

"...in his medical school a doctor receives a training which is more or less the opposite of what he would need as a preparation for psychoanalysis. His attention has been directed to objectively ascertainable facts of anatomy, physics and chemistry...His interest is not aroused in the mental side of vital phenomena; medicine is not concerned with the study of the higher mental functions, which lies in the sphere of another faculty. Only psychiatry is supposed to deal with the disturbances of mental functions; but we know in what manner and with what aims it does so. It looks for the somatic determinants of mental disorders and treats them like other causes of illness.

Psychiatry is right to do so and medical education is clearly excellent. If it is described as one-sided...In itself every science is one-sided. It must be so since it restrict itself to particular subjects, points of view and methods. It is a piece of nonsense in which I would take no part to play off one science against another. After all, physics does not diminish the value of chemistry; it cannot take its place but on the other hand cannot be replaced by it. Psycho-analysis is certainly quite particularly one-sided as being the science of the mental unconscious."

Freud, "The Question of Lay Analysis', 1926, Standard Edition, Vol. XX, p. 230-231.