Electrical machines are classified into two..

Motor.
Generator.
There are two kinds 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 motor , slip presents in asynchronous motor .At running condition slide of an asynchronous motor lies from 0 to at least one 1. . In asynchronous motor both starting and working torque is required. Asynchronous motor has moderate starting torque . Asynchronous motor is a single fed engine.In asynchronous motor field is stationary armature 12v Motor 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 power generation industry; they are rotated mechanically by a prime mover at synchronous acceleration and it generates three phase electricity. Image of PMA used in cars:
2. Synchronous motor: They are constant speed three phase machines capable of running at synchronous swiftness. They are mostly used in constant swiftness mechanical drives. They are better compared 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 quickness i.e. 3000 rpm. That is achieved through special constructional features in manufacturing this types of machines. There is no slip in synchronous machines like regular induction motors.

Normally three phase supply is available commercially and the design is also designed for the same. This is why ‘three phase’ is certainly added with synchronous machine name.