Caporegime
Likely (but I can't 100% confirm), that 1060 was ground up designed for the 14nm process, whereas the RX480 was intended for the failed 20nm process, and then got adapted to 14nm.
If Vega shows better power usage (as it is believed this is designed for 14nm directly), then it will confirm this.
Yeah i get the impression the RX 480 is a bigger version of a shrunk R9 285/380/X.
not that this is a bad thing they are actually very good GPU's.
But i do think Vega is the ground up new GPU and is where the real improvements are.