As regards alternatiors vs. generators, an alternator IS a generator, but it produces alternating current which is rectified to half-wave alternating current which can be used to charge a storage battery. The armature and field parts are reversed from their positions in an old-fashioned direct current generator, which also produces alternating current, but is internally rectified by the commutator. Since the heavy current is not carried by the commmutator and brushes, electrical and mechanical losses are far lower in the alternator type of dynamo.

For an alternative usage, read Alexis de Toqueville's description of the United States, wherein he describes the entire country as a dynamo.