Comparison between my wife's black n5 and my new red n5, I can definitely say there is an enormous difference between then. While the black one has the rubbery/ silk touch feeling, the red one has a 'matte' plasticky feeling. Being used to the black n5, I immediately noticed this when I received the red one today.
IMO the black one has a more premium and classy touch. This red one is going back to the store! Kind of disappointed really. Don't get me wrong, the color is nice but I expected the material to be identical to the black one.