Creatine select is mainly a creatine product with phosphates to better shuttle the creatine to muscle tissue. It works like regular creatine through conversion to ATP for energy and strength, but only better.
Muscle Synergy combines glutamine, HMB, and creatine in synergistic rations shown through studies to increase lean muscle tissue. I believe it works by allowing a greater retention of nitrogen which leads to new muscle of course. I may have forgotten one ingredient.
Beverly International Nutrition Support Forum 