The PS4/Xbox one are stupidly similar to each other, the problem with the Xbox One is the development tools and it has different approaches to parts of the hardware.
One could argue that the Xbox one is at a lower performance than it should be, so it *could* close the gap a little (As in, the gap is currently X, when it should be Y, based on their hardware spec).
So, PS4's currently performing at normal levels for itself, while the Xbox one is under performing.
But there's still a gulf of hardware between them at either rate.