Creatine and whey are two different things, creatine is used for energy in the body and whey is a protein.
Whey is protein, a fast digesting one at that too. It's used to supplement protein intake when you can't get enough from a diet.
Creatine on the other hand is used to supplement creatine in the body. For short bursts of high energy the body uses ATP, creatine is used to restore this basically.