motor power and chinese spindles power HELP

[Jonathan]

No, the 3-phase 3000rpm 0.75kW motor is exactly the same type of motor as the spindle motor. Squirrel cage is just another name for an induction motor.
The short answer is making the motor higher speed gets higher power density (i.e. more power for same weight). Also, the water cooling extracts the heat from the spindle windings far more efficiently than air cooling, so the conductors can be run at a much higher current density, so less mass in copper/iron is required.