Psychologists (PhD or PsyD) have doctoral level training and use different varieties of psychotherapy (i.e., talk therapy) as treatment for a wide range of mental health issues and life circumstances, such as trauma, anxiety and depression, psychosis, relationship issues, and life stressors.
A psychiatrist (MD) is a medical doctor with speciality in psychiatric care. Because of their training in medicine, they are able to assess overall physical health and prescribe medications for mental health (i.e., psychotropic medications). They are also qualified to provide psychotherapy (i.e., talk therapy), similarly to psychologists.
A neuropsychologist (PhD or PsyD) is a doctoral level psychologist who has specialized in understanding brain functioning. Neuropsychologists can provide neuropsychological assessments, to link specific mental health struggles to specific aspects of brain functioning.
A postdoctoral psychologist (PhD or PsyD) is at the highest level of training before becoming a licensed independent practitioner. Postdoctoral psychologists largely provide the same types of services as licensed psychologists while receiving supervision by licensed psychologists at a significantly reduced fee.