Many people confuse the work or rather definitions of a psychologist with that of psychiatrist. Both work in the field of mental health, however these are different qualifications, different types of degrees, and differ in application.
A psychologist holds a master’s degree specialising in a registered category of psychology, whereas a psychiatrist is a medical doctor that further specialises in psychiatric medicine.
Practically, psychologists primarily intervene or work through therapy (although this depends on the registration category – see what is a registered psychologist). Psychiatrists are more involved with medical management of individuals diagnosed with or seeking medical treatment for a psychiatric diagnosis.