It may be basic, but it is definitely the answer. However, it might be useful to think of the ramifications. A psychiatrist has been trained as a physician first and has then gone into psychiatry as a speciality. Their medical training makes an impact on how they view their patients, how they conceptualize problems, diagnose, and develop treatment plans. A psychologist has basically trained in the area of behaviour (clinical psychologists study HUMAN behaviour) and are usually trained as both scientists and practitioners. They do not come from a medical perspective in how they view and ultimately work with their clients. One is not superior to the other and they can work together with good results. But their training and backgrounds differ and these differences guide their practise.