I think you are trying to distinguish between a conventional generator and an inverter generator. A conventional gen is a single speed engine that drives a mechanical style generator. An inverter generator is a variable speed engine that drives an alternator which then has an electronic package that "inverts" the DC output of the alternator to AC.
Many conventional gens as the B&S you talk about also have a small DC output to charge external batteries. They are not "inverter generators".
I would expect anyone who has an "inverter generator" to know it(they cost a lot more); if they don't know you can assume they have a conventional gen.
Doug