Ketamine and Transcranial Magnetic Stimulation differ in nature and use. Ketamine is a medication that alters brain glutamate activity and can rapidly relieve severe depression or pain, sometimes with dissociative effects. TMS is a non-drug therapy that uses magnetic fields to stimulate specific brain regions for depression treatment without intoxication. Ketamine acts quickly but has side effects; TMS is gradual, non-invasive, and typically well-tolerated.