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.
12v Motor asynchronous motor.
The basic difference between asynchronous and synchronous motor , slip presents in asynchronous engine .At running condition slip 
of an asynchronous motor lies from 0 to at least one 1. . In asynchronous engine both starting and running torque is required. Asynchronous motor has moderate starting torque . Asynchronous motor is a single fed motor.In asynchronous electric motor field is stationary armature rotates .
Three phase synchronous machines possess 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 speed and it creates three phase electricity. Image of PMA found in cars:
2. Synchronous motor: They are constant speed three phase machines capable of running at synchronous speed. They are mostly used in constant velocity 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.
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 swiftness i.electronic. 3000 rpm. That is achieved through special constructional features in production this types of devices. There is absolutely no slip in synchronous machines like regular induction motors.
Normally three phase supply is available commercially and the look is also designed for the same. That is why ‘three phase’ is definitely added with synchronous machine name.