blush is for your cheeks. BP can either have shimmer or no shimmer, and are sheerer in color. they're meant to be used all over the face (no shimmer) or on the high points of your face (shimmer). they add a softened, diffused look to your face. the color can be built up and used as a blush, but they aren't intended for that. just like blush can be used to contour, but its not intended for that.