They have access to a fab process that is ~2 full generations more advanced than what Intel is shipping most their products in, and 64-bit ARM has one advantage

They have access to a fab process that is ~2 full generations more advanced than what Intel is shipping most their products in, and 64-bit ARM has one advantage over x86 (fixed-width instructions) which allow them to make a very wide core. Of those two advantages, the process one is a lot more significant. Their chip loses in single-threaded performance to AMD's newest, which are still one node behind Apple, but appears to be more power-efficient. I fully expect that once AMD gets on the matching node they will take the crown back, even in a laptop power envelope.