Luigi jumps higher, of course
Nintendo dropped a bit more info on New Super Luigi U today, the upcoming DLC for New Super Mario Bros. U. For starters, they've changed all the original 80 stages into almost a completely new game -- so it's not a wholly original experience, per se.
Luigi will also be able to utilize his signature higher jump mechanic, which allows him to access new areas, and makes him harder to stop after dashing. The DLC's stages are shorter, with less time to complete them (a 100 second timer was mentioned).
No pricing information was given, but it is coming this Summer on the Wii U, and I can't wait!