Psychologists have at least a masters but it is becoming more common to need a doctorate. They are licensed to diagnose mental illnesses and provide therapy. When you go to therapy this is often who you are working with. Psychiatrists are able to all that a psychologist can do but have a medical degree. This allows them to prescribe medication. They do evaluations for mental illnesses, diagnose, prescribe medications, and create treatment plans. They provide counseling regarding medications, but do not do as much therapy as psychologists do, though they can. Finally neurologists work with other problems relating to the brain, so things like stroke, hemorrhaging, coma, spinal cord damage, etc. They order diagnostic tests, diagnose problems, prescribe interventions and medications, assess patients, and manage care. They work both in and out of hospitals. These are very basic introductions to the differences of each field. If you are interested in any of them you should do research on that particular field, this explanation is merely to help you differentiate the three.
Susan Delphine’s Answer
Psychologists focus on therapy, and sometimes on testing that localizes where in the brain a person's symptoms come from.
Psychiatrists are medical doctors, which means they can prescribe medications and treat issues that require medication.
Psychologists are not medical doctors, but they help with mental health and behavioral counseling.
Neurologists study the brain and spinal cord. So you might go see one if you're having chronic headaches.
They all have some knowledge and background that overlaps -- especially psychiatrists and psychologists -- but they each specialize in a unique and specific set of skills.
A psychiatrist is a medical practitioner specializing in the diagnosis and treatment of mental illness.
A psychologist is an expert or specialist in psychology.
A neurologist is a medical specialist in the diagnosis and treatment of disorders of the nervous system.