I guess I would need to know more to fully understand. You said that you also experience depression, what kind of depression do you have? Was it diagnosed? If we know that, we can help you figure out how his is different from yours.

In a nutshell though, clinical depression should just indicate an overall feeling of sadness that could vary in intensity depending on the person, but that it's hard enough for him that it interferes with daily functioning. There's more criteria as well, but that's why more information would be helpful.