Many years ago when I was in school, there were supposedly 3 kinds of depression: manic-depressive depression, situational and major depression. Since then the DSM has been rewritten a few times and new names have been assigned to these disorders. As I understood it, situational depression was something that resulted from a sudden change in life-death of a loved one, house lost, divorce, etc. something with an abrupt onset and a relatively short duration of emotional change...6 months or a year, I think it was. Anyhow, things have changed with diagnostics and definitions and labels.
I thought my bout with depression was situational 5 years ago. Thought that it was brought on by 1) quitting smoking, and 2) loss in income due to weather interference with my business outdoors. So I started smoking and nothing changed. Then I began working regularly and still nothing changed. In fact, I could not get up and going to GET TO WORK, so I saw my doc and got on antidepressant medication and that is when my depression lifted. While the therapist I saw was understanding and helpful in being compassinate about both the smoking and the loss of employment, it was the medication that actually changed the way I felt on waking.
I am not sure that I would have the ability to discern one type of depression from the other once I am in it. I am scared to death of it, no matter what kind of depression it is. It is a matter of life and death to me, as far as I am concerned. It runs in my family,too.
Michael