I am aware of the following differences between the standard B17 and the B17 Champion Special:
small steel rivets
black painted frame
large hammered copper rivets
copper plated frame
I seem to recall reading that the standard B17's leather was thinner than the CS, allowing faster break-in. I know both B17s are more supple than the Team Pro, which I think is the hardest and thickest of them all.
Are there any other differences between the standard and the CS other than price?