I don't like Gatorade, so I don't have any packages handy to compare. I assume the ingredients are slightly different to accomodate making the powder version. It's like laundry detergent. The liquid and powder versions are slightly different. Some chemicals aren't readily available dry, while other chemicals may not last long when combined in solution, so the laundry folks have to tweak the ingredients.

Anyway, I suspect that some of the ingredients are different in the powder version of Gatorade. Maybe the sweeteners are different?