What's the difference between hypersensitivity and auto-immune disease, in the terms of immunology?

Very different: A hypersensitivity is generally what we call an allergic reaction. This is mostly to things you find in the environment, and most of the time is driven by an antibody called ige. An autoimmune disease is usually driven by igg antibody, and what is being attacked is something in the body that the immune system thinks is "foreign" and should be "dealt with" when it shouldn't be.