Electrical machines are categorized into two..
Motor.
Generator.
There are two types of motor.
AC motor.
DC motor.
There are two kinds of three phase motor.
Synchronous motor.
Asynchronous motor.
The basic difference between asynchronous and synchronous engine , slip presents in asynchronous engine .At 12v Motor running condition slip of an asynchronous motor lies from 0 to 1 1. . In asynchronous electric motor both starting and running torque is required. Asynchronous engine has moderate starting torque . Asynchronous motor can be a single fed electric motor.In asynchronous electric motor field is stationary armature rotates .
Three phase synchronous machines have got a stationary three phase armature and a wound rotor. They are of two types:
synchronous generator or Alternator: Main workhorse of the energy generation industry; they are rotated mechanically by a primary mover at synchronous swiftness and it generates three phase electricity. Picture of PMA found in cars:
2. Synchronous motor: They are continuous speed three phase devices capable of working at synchronous velocity. They are mostly found in constant rate mechanical drives. They are more efficient in comparison to induction motors.
A synchronous machine has derived its name from the idea that the rotor will rotate in synchronicity with the rotating magnetic field.
Simply speaking, for a 2 Pole machine (electric motor) the rotating magnetic field rotates at 3000 rpm; the rotor of synchronous 
machine also rotates at the same swiftness i.electronic. 3000 rpm. This is achieved through unique constructional features in production this types of machines. There is absolutely no slip in synchronous devices like normal induction motors.
Normally three phase supply is available commercially and the design is also meant for the same. This is why ‘three phase’ can be added with synchronous machine name.