brand to brand, not really.
couple of years ago nitrotech was tested and found that users had slightly more gains over others. but the reason was because they put creatine monohydrate in it, funny how muscletech never mentioned that in all their ads at the time. they said it was because of their revolutionary protein blend.
now milk blends have fared well in research over straight whey powders. in some instances, one could say that casein kicked wheys butt