Surface Pro with 4 hour of Battery?

Ok maybe someone can explain this to me better I currently use a Samsung Series 9 which has similar specs to the Surface pro. The Samsung has a core i5 (ivy bridge), 4gb of ram, 13.3in 1600x900 400 nit screen, and a 44wh battery in it. The Surface pro has a core i5 (ivy bridge) 4gb of ram, 10.6in 1920x1080 touch screen + Digitizer, and a 42wh battery. My Samsung gets near to 9 hours of battery life. Yet the Surface pro is being rumored to get 4 hours? That does not make sense to me. Two devices of similar size with similar specs to me seems like the battery should be closer.Does 1080p and a touchscreen really suck that much power or am I misunderstanding something.