I guess there could be extra band frequencies enabled for china's version among other things as it's also meant for LTE-CT version too, while global supposedly isn't. Also these versions are the very last before MM came along. I do know they were preparing for MM by merging partitions with those versions.
Where do you check kernel version in the rom package? I would like to check if xiaomi.eu 7.1.3.0 is based on the same china rom as 7.1.5.0.
In system info tap on kernel version a few times and it should take you to a test menu, in the test menu select the first option.