They're All Generators
Every device that converts mechanical energy to electrical energy is a generator. Initially, all the generators used in aircraft (and automobiles) produced Direct Current (DC). More modern systems employ generators that produce Alternating Current (AC). For systems in the vehicle that require DC, a transformer-rectifier is employed to make the conversion. As was mentioned earlier, the use of AC is beneficial because of weight savings and because there are no brushes required as in a DC generator.
Common usage is that AC generators are called "alternators". DC generators are referred to as "generators" but they are all generators in the end.
Hope this helps.