I'm not either hehehehe.......but seriously I think it's because it's what it says: alternator.......meaning it alternates putting out juice in a cyclical way or as needed, whereas the generator is constant output all the time above certain rpms. What this means to me is with an alternator, your voltage regulator wire always must go directly to the battery (with fuse or circuit breaker in line), so the system is always relying on the battery, so if it's shorted or dead .....SOL. With a generator, you can run the volt reg wire to the key switch (the battery wire is also there as well), but now you're directly wired, so the bike can constantly rely on the generator. If you need lights with a weak battery tho, you will also probably be SOL!