Did you actually make an effort to understand power factor? Do you understand that you can not determine the efficiency of a motor unless you know its power factor? Do you understand that power factor equals the cosine of the phase angle between current and voltage? Do you know how to measure phase angle?
It would seem that the answer to all these questions is "no".
Let me try to explain: For an ac load, current and voltage are only in phase if the load is purely resistive. For example, a light bulb. Motors do not generally present resistive loads; due to inductance, they are are partly resistive and partly inductive loads. A purely inductive load (a coil with no resistance) will have a current-to-voltage phase angle of 90 degrees and consumes NO POWER. Energy bounces back and forth between the coil and its power source, but the net power consumed is zero. Think of an inductor as an electric spring, storing and releasing energy. An electric motor is partly inductive and partly resistive, so the current to voltage phase angle is between zero and ninety degrees. For example, it might be 45 degrees, which would give us a power factor of .707 (cosine of 90 degrees).
Going back to your example, your AC motor is rated at 759 volt-amps (NOT 759 watts). At a power factor of .7, 759 volt-amps is 531 watts. At a power factor of .6, 759 VA is 455 watts. These are typical power factors for small motors.
The second erroneous assumption you made was to assume that the current rating for the motor is at the rated power. Unless specifically stated otherwise, the current rating is going to be greater than the current at rated power. That's because the wiring and circuit breakers for the motor need to be rated to handle a brief overload, such as starting current or during an intermittent high load.
Now with a dynamometer and other appropriate test gear, we could objectively compare the two motors. But that's not really necessary; electric motors are pretty efficient, be they ac or dc. Both motors have their advantages and uses. And there are many subtypes of ac and dc motors that have specific advantages in certain applications.
Also, regarding the difference in DC and AC rating for circuit breakers, that is easily explained: alternating current is interrupted 120 times per second, which means arcing is reduced when switching an ac load versus a dc load.
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