Sorry but ARM does have an advantage as a 10 year old ISA vs one that still carries the baggage of 40 plus years of development. The exact size of that advantage isn't clear and may be small vs implementation specific features and process differences, but it's still there.

Plus, there have been features of Arm implementations that have clearly given them power efficiency advantage vs x86, big.LITTLE which is now coming to Mac and up until now has not been a feature of x86 implementations.