I don't see why either 220 or 110 supply will inherently have a lower or
higher power factor. The current and voltage should not necessarily have any
phase shift differential because of the voltage difference.
On the other hand, winding losses for a given horsepower motor should
increase due to a lower voltage and thus a higher current being required,
unless the motor has been wound with considerably larger gauge wire. Unless
the motor has been designed and built to compensate with lighter parts
elsewhere or lower friction elsewhere, it seems that a lower voltage 110
volt / higher current motor would be less efficient.