What is difference between G7/8'' and 15/16-14NPSM ?

The G7/8" and 15/16-14NPSM inlet thread standards differ primarily in thread angle, pitch. The G7/8" follows the BSPP (British Standard Pipe Parallel) standard with a 55° thread angle and 11 TPI (threads per inch). In contrast, the 15/16-14NPSM adheres to the NPSM (National Pipe Straight Mechanical) standard with a 60° thread angle and 14 TPI.Although there are some differences in specifications,but it is not affected in the actual use of the toilet fill valve, and the G7/8 "and 15/16-14NPSM can be connected to the same water inlet pipe, and normal use.