Electrical machines are classified into two..
Motor.
Generator.
There are two kinds of motor.
AC motor.
DC motor.
There are two types of three phase motor.
Synchronous motor.
Asynchronous motor.
The basic difference between asynchronous and synchronous electric motor , slip presents in asynchronous engine .At running condition slide of an asynchronous electric motor lies from 0 to at least one 1. . In asynchronous electric motor both starting and running torque is necessary. Asynchronous electric motor has moderate beginning torque . Asynchronous motor is certainly a single fed 
engine.In asynchronous 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: Primary workhorse of the energy generation industry; they are rotated mechanically by a primary mover at synchronous speed and it generates three phase electricity. Picture of PMA found in cars:
2. Synchronous motor: These are constant speed three phase machines capable of operating at synchronous velocity. They are mostly used in constant acceleration mechanical drives. They are better compared to induction motors.
A synchronous machine has derived its name from the concept that the rotor will rotate in synchronicity with the rotating magnetic field.
In other words, 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 rate i.electronic. 3000 rpm. This is achieved through particular constructional features in manufacturing this types of devices. There is absolutely no slip in synchronous devices like normal induction motors.
12v Motor Normally three phase supply is available commercially and the look is also designed for the same. That is why ‘three phase’ can be added with synchronous machine name.