Psychiatry is a specialist field within medicine (other specialist fields within medicine include neurosurgery, neurology, cardiology, pediatrics etc). Psychiatrists train to be medical doctors, and then specialize in a particular area (such as primary care, or psychiatry or whatever).

Psychology is a field within university departments (other fields include biology, sociology, chemistry, computer science etc). One field within psychology is abnormal psychology. People can train to be clinical psychologists and gain accreditation to practice as clinical psychiatrists - treating people with mental disorders. Other fields within psychology include social psychology, organizational psychology, neurological psychiatry, criminal psychology, and so on.

One way of capturing the difference is that psychologists treat by way of TALK THERAPY whereas psychiatrists treat by way of PHARMACOLOGICAL INTERVENTION (medications and psychosurgery). This distinction is blurring as some psychologists (neuropsychologists) have started to try and get licenses to prescribe medication (where prescribing medicine is typically something that only doctors are allowed to do). The distinction is also blurred historically, as Freud advocated a particular variety of talk therapy (psychoanalysis). It used to be the case that one had to be a MD (Medical Doctor) before one was allowed to train as a psychoanalyst - but now the doors have been opened to clinical psychologists and master of councelling people (a field within education) and social workers (not sure where that falls. Sociology?). Another historical distinction is that the birth of psychiatry as a specialist field is sometimes placed at the birth of the idea that the asylum could be THERAPUTIC in treating people with mental disorders. The idea that running an asylum in a THERAPUTIC manner took a MD with special attributes.

Doctor of Psychology (PsyDoc) is a fairly recent qualification. It contrasts with the more traditional Doctor of Philosophy - in Psychology (PhD) in that it is PRACTICAL rather than RESEARCH focused. Matter of ideology, really. Some people thought that training for research (e.g., learning how to conduct experiments, learning how to analyze statistical data and so on) wasn't necessary in order for one to be a good clinician. Indeed, that spending time learning those things was taking time away from the practice of psychotherapy. So... The PsyDoc qualification (non research academic doctor - if that isn't a contradiction in terms) was invented with the intention of providing much more hands-on experience / practicum with less emphasis on research. The idea is that that will enable the person to be a better clinician in practice.

The Boulder conference was the start of this (there was much debate - and the debate remains).

Part of the debate is over... Whether the Doctor of Psychology should be an academic qualification where what has traditionally been the main feature of a university qualification (as distinguished from a technical college qualification) is RESEARCH. But then... Similar issues arise with education, nursing, and indeed there are similar issues with law, engineering, medicine etc...