The 6 wires of the two-phase stepper motor are respectively: two of them are the common ends of the A winding and the B winding, and the other four are the phase wires of the A winding and the B winding.
The generation of bipolar stepper motor and unipolar stepper motor is from decades ago, because the stepper motor drive circuit is more expensive, if the bipolar drive circuit is much more expensive than the unipolar circuit, so many years ago, the unipolar stepper motor is a lot. However, with the cost of the stepper motor drive circuit getting lower and lower, coupled with the emergence of some very cheap driver chips, the application of bipolar motors has increased.