Depression. Classification is based on severity of symptoms, duration, & how such interferes with daily functioning, from milder forms such as grief reaction, to dysthymic disorder, to major depression, to psychotic or bipolar depression.
Depression. Clinical depression means you have met criteria suggested by dsm 4 tr or now dsm 5, you can google it non clinical depression may mean that we feel sad on and off but doesnt impair our functioning or cause distress.
Subclinical. Some illnesses do not present the usual signs and symptoms and may not meet the usual diagnostic criteria, or are mild enough to not warrant the diagnosis. The term sub-clinical is often used for such circumstances. Clinical depression usually denotes that the diagnosis was made by a doctor, not just a feeling of the patient.