lol..here we go again...it will NOT use less power on 220
volts times amps equals watts.
it will use half the amps (because it is in 2 wires)but you are pulling the same amount power because you are using 2 legs of 120.
so 600 divided by 120 is 5 amps
600 divided by 220 is 2.5 amps per leg...