The difference between mild depression and major depression is as follows: 1. Major depression is usually accompanied by severe self-injury, suicidal tendencies or behaviors, while mild depression may be accompanied by distress, depressed mood, diminished interest, and mild thought retardation, and patients need to have symptoms lasting more than two weeks to be diagnosed with depression. Major depression is accompanied by significant thought retardation, diminished interest, low self-esteem, and the most typical symptoms are self-injurious and self-harming behaviors or ideas.2. For treatment, mild depression requires psychotherapy, cognitive behavioral therapy. Major depression requires antidepressant medication, commonly used are sertraline, fluoxetine, citalopram, etc. Severe depression with self-injury, suicidal tendencies, may also require twitch-free electroconvulsive therapy.