Which operating system and program are you using to measure wattage? Sometimes some programs like GPUz misread the power state and read it as one level higher which would account for the 20w difference sometimes under Windows. I'm assuming the fan profiles and RPM are the same. It's possible they made hardware changes on Rev 2 but I haven't pulled mine apart to compare my rev 2 to pictures of rev 1.
I'm using HiveOS, having just switched from Windows 10. However, I am still using Phoenix Miner, which is what I was using in Windows as well. Showed the same wattage difference between rev 1 & rev 2