U.C. is restricted to the large intestine (colon). Crohn's Disease can be in any part of the digestive tract, from mouth to anus. It is usually found in the small intestine. But--here is where it gets complicated--you could have inflammation of the colon and it be Crohn's disease not U.C. This is because Crohn's can be anywhere in the digestive tract. So, in sum, if you are having inflammation of the small intestine it is likely Crohn's Disease (although there are other possible causes). Hope this helps!
Best,
Matt (team member)