I find the MBA vs Surface Pro 2 comparison to be more than slightly misleading: >The screen is somewhat lower resolution No, 1920x1080 isn't only somewhat higher than 1366x768, it's 1.97 times the number of pixels and the panel is PLS unlike the TN in the MBA. The display is the component that eats up the battery the most when doing things like Wi-Fi browsing, even the battery life of the MBA scales heavily with the…
Indeed: it is a known fact that Apple gets custom exclusive low-clocked CPUs from Intel. Apple's chips are closer to "Y" class Intel Chips, which are designed for exceptionally long battery life at cost to performance.
Overall, I think the better screen, Wacom Digitizer, and faster CPU will all add up to the difference between the Surface2 and MBA.