The difference between duodenitis and duodenal ulcer is as follows: A diagnosis of duodenitis under endoscopy indicates inflammation in the duodenal bulb or descending part, featuring patchy congestion or spotted, erosive conditions identified during the endoscopic procedure, which lead to the diagnosis of duodenitis. If isolated or multiple ulcerative lesions are found in a certain area, it is diagnosed as a duodenal ulcer. Benign ulcers typically have clear boundaries, with surfaces covered with white moss or blood scabs, and the surrounding area may exhibit redness, concentrated mucosa, among other characteristics. Depending on these different presentations, there are different stages of the disease. Both duodenitis and duodenal ulcers are considered benign lesions.