Your doctor: Your doctor can talk to you about the differences between colitis and diverticulitis. Diverticulitis is an inflammation of the outpouching in the colon.Diverticular disease is an abnormal but common finding in the large intestine. Colitis is general inflammation of the entire large intestine.our doctor: Your doctor can talk to you about the differences between colitis and diverticulitis. Diverticulitis is an inflammation of the outpouching in the colon.