Of course there is. X1C flexes like it was made out of rubber. I can hold the edges of the display and it's terrifying what how much you can twist them. The aluminum case of the MBP tolerates heat better, the X1C get really loud under load while the MBP is much quieter. Touchpad is just incomparable.

And of course, if you need OSX for work then only MBP provides that.