What are the differences between Crohn’s disease and ulcerative colitis?

One of the main differences between these two gastrointestinal conditions is the part of the digestive tract that they affect. Ulcerative colitis occurs in the colon and rectum (large bowel), while Crohn’s disease can occur anywhere in the digestive tract. So, for people with ulcerative colitis, abdominal pain is often limited to the left side of the abdomen, while people with Crohn’s disease may have abdominal pain anywhere in the abdomen. Since Crohn’s disease affects more of the GI tract, it can cause different symptoms that are not seen with ulcerative colitis. These may including mouth ulcers (canker sores) that develop around the base of the gums and anal fistulas (anal fissures) which are splits or tears at the end of the anal canal.