The main differences between the alternator and generator are given below: A generator is a machine that converts the mechanical energy of the main engine into direct current or alternating current, while an alternator is a machine that converts the mechanical electricity of the main engine into alternating current. The output power of the generator is not much stronger than the alternator's output power. The alternator contains a spinning magnetic field, while the generator contains a rotating magnetic field to produce a low-voltage constant magnetic field and a high-voltage magnetic field. The alternator can’t charge a fully dead battery, while the generator has the ability to charge a fully dead battery. In the generator, the rotor provides the input power, while in the alternators, the stator provides the input. The output voltage of the alternators is variable, while the generator output voltage remains constant. The generator armature is static but alternates within the generator.