The major difference between an AC and a DC generator is that a DC generator has:

A DC generator is distinguished from an AC generator primarily by its use of a commutator. The commutator serves a critical function in converting the alternating current generated in the armature winding into direct current. As the armature rotates within the magnetic field, an alternating voltage is induced in the winding; however, the commutator rectifies this alternating current, providing a unidirectional output suitable for DC applications.

In contrast, AC generators, commonly referred to as alternators, utilize slip rings that allow the output current to remain alternating, thus not requiring any conversion mechanism. The rotor and stator components are present in both types of generators; the rotor is the rotating part, while the stator is the stationary part housing the windings. However, it is the presence of the commutator that fundamentally differentiates a DC generator from an AC generator by enabling the transformation of AC into DC.