What’s the difference between Aspirin, Advil, Tylenol, and Ibuprofen?

John S asked: I was wondering what the differences between these drugs are. The following would be nice in any responses:
-What illnesses are they intended to treat?
-What is the working drug that is present in them?
-What are the Side effects?
Also which one is the most effective for:
-headaches
-muscle pain
-migraines
Thanks!!!!