I agree with Belleenstein and you also can have both. I have both. In fact because I have IBS I didn't realize that I also had Crohn's until I had to have a resection because of a fistula to my bladder. IBS doesn't effect the lining of the intestines where IBD does. IBS is considered a malfunction of the colon and not a disease. I hope that helps.
Vicky / 47 years old
DX'd with Crohn's during a resection August 2006
DX'd with Steriod induced Diabetes November 2006
Considered in Clinical remission but have minor signs of disease activity
Daughter (26) also has Crohn's since she was 12.
Currently on 4000mg of Pentasa only for Crohn's
No longer able to take 6-MP because of Bone-Marrow Suppression
Cymbalta, Metformin, Lipitor