What is the difference between armature and rotor?

Hint: When attempting questions like the one given to us above, keep in mind the different concepts and terms surrounding armature and rotor like generators and motors, and the other parts which make up these appliances and what is their use and what is the principles on which they work.

Complete step-by-step solution:
A machine or mechanism which readily converts mechanical energy to electrical energy is known as a generator. The concept behind this mechanism is derived from Faraday’s law of Electromagnetic induction or EMI and we can classify generators into two types namely AC and DC generators.
Working principle behind this generator is that it uses a rectangular coil with multiple copper wires wound around an iron core, and this coil is termed as Armature. This coil is a device used to increase the magnetic flux, which is basically a measure of total magnetic field lines passing through a given area. The greater number of lines, more will be the magnetic flux, hence more will be the magnetic properties of the apparatus. So basically, an armature is used to carry current while the windings produce the required magnetic field or flux required to excite the generator.
In other words, Armature can also be termed as the part of the generator which is used to produce the necessary voltage, because the number of coils of wire are a great amount and will hence be able to carry the full load current of the generator.
Now coming to the motor, this machine converts electrical energy into mechanical energy. It too has two types; AC and DC motors.
A rotor is basically – as the word suggests – a rotating electrical component in the mechanism. It is located inside the stator and its objective is to rotate so that in turn the motor shaft or generator rotates.
So basically, the rotor consists of a field magnet which rotates while the rotor remains stationary and on the other hand the armature carries current and is stationary and part of the stator.

 Note:While the principle of generator is to convert mechanical energy into electrical energy, it is the opposite with Motor which uses the principle of converting electrical energy into mechanical energy. Both have two types, AC or alternating current and DC or direct current types of generators and motor.