Surface pro Battery

So ... the Acer iconia W700 manage to get a litle over 7h of battery life from a 54Wh battery and the Surface Pro only gets 4h at best from a 42.5Wh battery ?

WTH has microsoft put inside it to waste so much battery life ? the hardware inside is almost the same , so how is the surface using so much more power ? with the same consumption as the W700 the 42.5Wh battery should be able to give around 5.5h , or at least 5h but under 4h is too low....