There are 2 drive systems - DC Drive and the newer AC Brushless. For visual identification, all DC Motors are round and AC Motors are square with Quick Disconnect cable plugs.
(However please refer to the model/part number printed on the motor when ordering)
Most rotary AB axes use DC motors even if the XYZ are AC motors.
When replacing a motor the Balance/Signal Gain/Compensation tuning of the machine's amplifiers needs to be carried out.