"Joseph Meehan" wrote:

If you mean how much total electrical power (and cost) it uses per minute...

Then you seem confused. "Power per minute" is meaningless,
like "miles per hour per hour."

Generally the larger units are more efficient using less total electricity
to produce the same amount of benefit and thereby often run less long so
over a 24 hour period they may use less total electricity.

As in "electrical energy," ie kilowatt-hours, ie kilowatts X hours of use.

Mikepier wrote:

Very simply put, a 220V unit does not use less electricity than a 110V
unit. It does run more efficiently though than a 110V...

Not much, I ween.

When you pay your electric bill, you pay for watts.

No. That's power, the rate of energy usage. We pay for energy usage,
ie power times time, like total miles traveled, vs miles per hour.

Lets say you have 2 identical 10,000 BTU A/C's.

A Btu is a measure of energy. Heat power is measured in Btu per hour.
Power is the rate of energy useage over time.

Now as the other poster stated. Watts=V*A...

Times the power factor, eg 0.8 for a small motor
or 0.4 for an old undercounter fluorescent light.

...because the 110V unit uses 10 amps, there is more of a voltage drop
across the electrical wires from the breaker panel to the A/C. Resulting
in reduced voltage at the outlet, which makes the A/C run less efficient.
But the 220V unit only uses half the amps, resulting in less voltage drop,
less heat across wires, more efficient.

IME, real numbers would show a miniscule efficiency difference.

Nick