Yeah, I heard the same about how UC and Crohn's affect the bowel and I think I also remember my doctor explaining to me that UC typically affects the whole colon whereas Crohn's colitis often has patches of healthy colon in between the affect areas.
And, Sally: Up until recently I was on Lialda for my Crohn's (four times daily), but was taken off because it was not working for me. I have heard good things from others, though, about it inducing/maintaining remission, so really it's just that everybody's different.
I'm sorry to hear about your diagnosis confusion, it must be very frustrating. I know that the treatments for UC and Crohn's are pretty similar, if not interchangeable, so at least you know you're not being treated for the wrong thing. Good luck with the Lialda, I hope it helps.