This is the simple way of looking at depression versus sadness.
Although depression is often thought of a being an extreme state of sadness, there is a vast difference between clinical depression and sadness. Sadness is a part of being human, a natural reaction to painful circumstances. All of us will experience sadness at some point in our lives. Depression, however, is a physical illness with many more symptoms than an unhappy mood. The person with clinical depression finds that there is not always a logical reason for his dark feelings. reference: Nancy Schimelpfening
I have clinical depression................people that do not have this dx have a hard time understanding exactly how we feel.
Hugs to you kiddo.Kitt