[marty888]

Hey Cleansing, 2 completely different products, protein is essential for muscle repair and growth. Creatine is a great supplement and will increase size and as Fub mentioned a lot of that is through muscle voluminzation, through drawing water into the muscle cells as muscles are around 70% water.
It will also give great increase in strength, I can generally increase my bench by 10% and put on about 12lbs in a 6 week cycle when I am using it. The down side to the holding water is that you can also hold it around the stomach.
Generally when you stop taking it you will probably lose about 50% of the gains. Its also important to drink a lot of water.
Protein I use year round, creatine I tend to cycle on and off depends on my goals.
If you have to choose protein is the more essential so that would be my choice.