Assuming you are gaming, either will do but I think it should be obvious that the m14x has a more powerful, speedier CPU (just look at the clock speeds). You certainly don't need the i7-3820qm to game on a 1600x900 screen, but maybe you want the power for something else, I dunno.
If you are comparing the GPUs:
-m11x runs NVIDIA GT540m on a 1366x768 screen.
-m14x runs NVIDIA GT650m on a 1600x900 screen.
The m14x has a better GPU for sure. But for the m11x resolution and price, the 540m is fine. It's not going to blow you away, but then again its a lot less money than the other.