What is the difference between ascorbic acid and vitamin c. what was it's uses?

One and the same: Ascorbic acid is the chemical name for vitamin c (just as pyridoxine is the chemical name of vit b6 etc.). Vit c is an essential nutrient for every cell of our body.We need it every day as we can't store it.It's crucial for the health of skin, connective tissue, immune system, preventing heart disease etc. See http://www.Lef.Org/magazine/mag2008/apr2008_newly-discovered-benefits-of-vitamin-c_01.Htm.