According to IGN, the PS Vita version of Rayman Legends is missing around 28 levels. The article states,
The 28 levels in question comprise the Invasion challenges, a hardcore speed-run mode that mashes existing levels together. Posters on NeoGAF note that the total number of collectible Teensies in the Vita version is reduced from 700 to 615 as a result.
This is a very strange omission from the game, seeing as last year’s Rayman Origins on the Vita contained all the content its console counterparts had. Even stranger is that Ubisoft did not mention these levels would be missing before release. Hopefully fans wanting to play the game on the Vita, will get get them as free DLC.