What is difference between niacin and niacinamide?

Lipid effect, flush: Niacin is a b vitamin that is often used to treat lipid (cholesterol and triglyceride) disorders. Nicotinamide is another vitamin in the vitamin b group. Although Niacin and nicotinamide are identical in their vitamin activity, nicotinamide has no significant cholesterol or triglyceride effects. Also, nicotinamide does not cause skin flushihg that can be a limitation to use of niacin.