What is the difference between colitis disease and diverticulitis?

Very different. Colitis is inflammation of the colon. It is commonly seen with inflammatory disease of the colon (ulcerative colitis). Any area of the colon can become inflamed with this. Diverticulosis is having small pockets that poke out of the bowel wall. Diverticulosis is when one of these pockets gets infected or inflamed. This is usually more localized, like in the left sigmoid colon.
Diverticulitis colit. Colitis is inflammation in the inner lining of colon, it can happen due to inflammatory bowel disease like ulcerative colitis and crohns disease, and certain infections.And diverticulitis is an infection in the diverticuli which are puches in the wall of colon, and need to treat with antibiotics like Flagyl and cipro, (ciprofloxacin) sometime surgery.Colitis is treated with antiinflammatory drugs asachol and prednis.