What is the difference between psychotic depression, regular depression and schizophrenia?

Symptoms.: "regular depression" is major depression without psychosis. Psychotic depression is major depression with psychosis. Both of these illnesses are disturbances of mood and the mood symptoms predated the psychotic symptoms. Schizophrenia is a thought disorder which may have some mood symptoms, but the psychotic symptoms precede the mood symptoms. Still pretty confusing, yes?

Major symptoms: "regular depression" refers to sustained depressed or irritable mood & changes in sleep, appetite, & energy level, maybe suicidality. Sometimes, with severe depression, people have hallucinations or delusions, e.g., "my body is rotting." they typically come after the depression starts and relate to depression. Schizophrenia is the hallucinations and delusoins without prominent depressive sxs.