What can i do to distinguish between feeling down and feeling depressed?

Severity: Feeling down is usually temporary and is caused by some sort of stress. Despite feeling down, one is usually able to function at home/work. With clinical depression there are more symptoms present such as poor concentration, change in sleep/appetite, fatigue, hopelessness, loss of enjoyment and sadness. Depression is more severe, can last longer and impair one's ability to function.