The difference between the small intestine and large intestine is:

Concept: The intestines are a major part of the human digestive system. They are tubular structures that help in attaching the stomach to the anus. Intestines are further divided into small intestines and large intestines. The small intestine has a smaller diameter in comparison to the large intestine. 

The small intestine is around 7 meters in length whereas the large intestine is 1.5 meters in length. The small intestine is divided into three parts namely, duodenum, jejunum and ileum. The large intestine is divided into three parts namely, colon, caecum and rectum. The actual digestion of food takes place in the small intestine, and it absorbs the nutrients present in the food material. No digestion takes place in the large intestine, and it is responsible for the re-absorption of water and electrolytes.

Hence the correct option is B.