wat is the difference b/w ATP n ADP ???? PLS XPLAIN IN DETAILS...

Adenosine-5'-triphosphate (ATP) is a nucleoside triphosphate used in cells as a coenzyme. ATP consists of adenosine — composed of an adenine ring and a ribose sugar — and three phosphate groups (triphosphate). Adenosine diphosphate, abbreviated ADP, is an important organic compound in metabolism and is essential to the flow of energy in living cells. A molecule of ADP consists of three important structural components: a sugar backbone which is attached to a molecule of adenine and two phosphate groups bonded to the 5' carbon atom of ribose.