HIMARS uses a weird intermediate caliber (227 mm) that neither China nor Russia use. It has mediocre 90 km range.
For China and Russia it's 122 mm light MLRS with 50 km range and 300 mm heavy MLRS with 120-160 km range.
and for China, PHL-16 also has options for 370 mm (very heavy MLRS) with 200 km range and 750 mm (multi SRBM) with 380 km range.
The difference in accuracy of GPS vs Glonass accounts for difference between US and Russian rockets. Beidou is equally or more accurate than GPS.
The main advantage of HIMARS is that it's modularized and can load all rockets from a prefilled box while Smerch has to individually load rockets. China's new PCL-191 and PHL-06 systems are all modular.