Sure, the fab size is part of the story, but we have also seen a general tendency for efficiency from Arm chips and the reason that they are used in mobile devices. Apple has also been willing to spend money on larger caches and wider buses in their SOCs to remove bottlenecks. Finally, Apple tunes the processor performance to optimize for processes that Mac OS uses a lot. That is possible because of their tight vertical integration and I have not seen on the more heterogenous Windows/Linux + Intel environment.