I was diagnosed with that last October - major depression, severe, recurrent- I sat in the room with the psychiatrist and TREID to explain how I felt and how long it has gone on for, and my past and what I did to cope with it. He explaned since I stopped doing those things there was no buffer anymore, which is why it was becoming too much and decided to seek help.

I believe the difference is the severity and cause, depression alone maybe be cause by an event or something while major depression is something that goes on for while, with seemingly no cause. Don't quote me on that though. I don't really know if the treatments are different because I have major depress. I imagine them being similar.

Don't be scared, get the help and find out. Honestly I was relieved that I did have something, so there was a way to try and make it better. btw I used to take those test online as well. You should go to a doc and find out. Its the first step in trying to fix it. Good luck!!!