Creatine releases a material (I forget what it's called) which combines in the muscle to form ATP which is what the muscle uses for energy. By supplying more of the necessary material to create ATP, you can do more and/or heavier reps which will allow you to tear down the muscle tissue faster hence giving you strength and size increases at a faster rate. Gluatamine is needed to help rebuild that muscle tissue and BB especially, can become depleted in glutamine. Glutamine will help you recover faster, you need it for protein synthesis. Glutamine also causes extra growth hormone to be released which would certainly lead to muscle growth. So personally, if you're trying to gain strength and get bigger, I would use both.
Train Hard Or Go Home