To be pedantic everything that produces electricity is a GENERATOR, and usualy comes as either a dynamo or alternator.
Now even a dynamo produces ac in the windings that is converted to dc by the brushgear, its a very complicated explanation that im sure can be googled, an alternator changes ac to dc with a rectifier using diodes which have no moving parts.
In a dynamo the brushes have to carry the full charging current and so need to be large and hard whilst alternators can be permag and vary output on revs or have a dc fed rotor which needs a lot less current needing tiny brushes.
I pdi'd one of the first GL 1000 in the UK and there were a few "teething" problems Honda said nothing about like the crown wheel/shaft spline drive
Hope that helps a bit