How does inflammatory bowel disease differ from ibs?

Significantly: In ibs the bowel is anatomically normal, but responds more intensely to stimuli. Anemia, weight loss, and bloody diarrhea are unusual. Surgery is not a part of therapy. In ibd (inflammatory bowel disease) at least some layers of the intestine are diseased. Ulcerative colitis can be cured by removal of colon and rectum. Crohn's disease may involve any part of the GI tract and cannot be cured.

Very different: Inflammatory bowel disease is a few well defined conditions characterized by inflammation , visualized and confirmed by biopsies in the colon. The long term complications are often severe and the treatments are well defined irritable bowel syndrome, though more common, is not well defined. Main symptoms are constipation and or diarrhea. Similar names very different conditions.

Function vs Organic: Ibs is purely a functional disorder or bowel regularity and pain perception. Ibd is an inflammatory condition of the bowels that causes many sideffects as pain, bleeding, diarrhea, weight loss.