Who knows, both motors were built completely in China. There isn't much of a difference. The G had a full length pole piece that protruded past the top plate. The H model is flush, in preparation for "upgrading" to the supercharged nonsense. I'd say, if you took a gauss meter to the gap, all things being equal, you'd measure a tad more at some point in the gap on the H, simply because of the stray field not being able to go up the pole. Nothing audible though in regards to the flux density alone. The inductance over excursion has to vary a bit versus the longer pole model. The supercharged version has an aluminum ring above the neo ring that does nothing for mitigating inductance.