There are differences but they are probably more effective from a marketing standpoint than a physical one. The Blend has somwhat less sidecut, no metal, less sidecut in the back 1/3 of the ski and graphics that seek the cool. The Blend has more tail rise but the splay is similar. Tip rise and profile are near identical. The P-100 is a bit stiffer torsionally, feels more nimble, and grips a bit better. Flex is similar. For hard snow, the P-100 gets the nod, for soft snow, it won't matter very much, for riding switch and cool factor, the Blend has the edge.
I skied them back to back but it was on steep firm snow (that's what was available) and the only thing I could connect was the better grip and more nimble feel on the P. OTH, the Blend wasn't bad at all it just required that I soften my outside ankle a little to keep it from chattering at the end of the turn. The Blend felt maybe a little more damp.