That depends on your definition of "A LOT". Both displays are WXGA+ LED backlit displays of comparable brightness. As such, I would expect the 14.1" model to consume 0.5 to 1.5 watts more than the 12.1" model. This can be rather significant when you consider the idle power consumption for the x200s with SSD and SL9400 is between 6 and 9 watts (depending on display brightness and radio status). The biggest difference though is still battery capacity. The x200s offers a 4 cell at 28WHr, a 6 cell at 56WHr, and a 9 cell at 84WHr. Conversely, the T400s only offers a reduced capacity, albeit flush, 6 cell at 44WHr. Therefore, even with identical power consumption the x200s 6 cell should get 27% better battery life than the T400s (56/44 = 1.27).