Vita has a mobile GPU. That kind of cards are designed with power consumption in mind, so they can't beat a desktop or console GPU of the same time frame. Current mobile GPUs can't even come close to PS3 or 360. Vita has one of the most powerful mobile GPUs, but it isn't stronger than a PS3. Vita uses it qHD screen to help when closing that difference (qHD is 1/4 of 1080p or 1/2 of 720p).
Wii U has a modern GPU, so it isn't way stronger than Vita and stronger the PS360. Of course, that isn't a fair comparison. What happens here is that Vita is specially strong for a portable and U isn't as powerful as the other next gen consoles (we only know PS4 now, but it's pretty much impossible that 720 won't beat the Wii U, since it will be more comparable to PS4 power wise).








