Both the small intestine and the large intestine are important organs of the body. The main difference between the small intestine and the large intestine is in the morphology and function: 1. The upper end of the small intestine starts at the pylorus and the lower end connects to the large intestine. The small intestine is longer about 4-6 meters, the lumen is thinner about 1.5-4 cm, the surface of the intestinal wall is smooth and divided into duodenum, jejunum, ileum, etc. The large intestine is shorter about 1.5 meters, the lumen is thicker about 6-7 cm, the intestinal wall is thin, the large intestine includes ascending colon, descending colon, cecum, rectum, etc. 2, the functional differences. The small intestine is the main digestive and absorption site of the body. When food reaches the small intestine through the stomach, the nutrients in the food, such as minerals, vitamins, proteins and fats, are absorbed by the small intestine mucosa. The large intestine mainly absorbs food residues and water from the small intestine, produces and stores feces, and finally expels them from the anus.