How are sadness and depression different in your mind?

Sadness and depression sometimes get confused and put in the same corner, but I think they are totally different. In my mind, I think of sadness as a feeling that is felt during certain moments, whereas depression is a state of mind. You might feel sadness while you are depressed, but I don't necessarily think that being sad causes depression. I think that depression is also more of a condition that interferes with your daily life and needs support and care to overcome. Sadness is a part of life, and it's healthy to feel and go through it at times because it's temporary and has a reason for being felt. Someone (can't remember who) described sadness and depression as the ocean, where one wave crashing over you is sadness, and depression is the whole ocean rising around you.