No difference at all.
Watts=Amps x Voltage
Your amp draw is the workhorse so if ya want to cut down on the bill or possibly double the wattage with no increase switch to a higher voltage. I assume your using 110v at the present so you have about a 4 amp draw at 400w.
W=A xV
440(400w)=4x100

Now put that into a 220V system

440=2x220

Just dropped the ol' electric bill down to half!