At a basic level, there are no differences in that all of these mental health professionals talk to clients to help them solve their problems. At another level, there are significant differences in education and training that can impact the type of help you receive. For instance, typically the terms therapist, psychotherapist, psychologist and psychiatrist denote practitioners with a doctoral level of training, while the other terms denote practitioners with a master’s level of training. But I believe that what determines how much a client resolves their problems while in treatment lies more within the client than within the therapist (such as the desire to get help and the determination to persevere until the goals of psychotherapy are met).