The NV 55 A flex profile is stiffer than the DHI A Flex, so it will play stiffer. The NV also has a stiffer torque (3.9 vs 5.9), which will also make it play and feel stiffer.
No idea why one is designated a “distance” and the other is both. I think all manufacturers will say that a 50ish gram version of a shaft will help with distance. The stiffer profile of the NV might yield more control for some, so saying it provides both improved distance (due to weight) and accuracy (overall stiffness) would be a reasonable claim.