Difference is in calibration, and graduation steps. HX is 3% at 15% of scale, while the H is 3% at 20%. H is a 1 lb/in graduation, while the HX is .5 lb/in. Had to go to product resources and then Customer print to find the info.
ANSI B107.14M was superseded by B107.14, which has been consolidated into ASME B107.300-2010