Is not just MP diff. Is the sensor design, lense type, aperture size, pixel size etc
Redmi Note 5 China
Rear: Samsung 12MP S5K2L7,
1.4μm Rear Camera, f/1.9 Aperture +
Samsung 5MP S5K5E8
1.12μm, f/2.0 Aperture
Front: Omnivision 13MP OV13855
1.12μm, f/2.2 Aperture
________________________________________
Redmi Note 5 Pro India
Rear: 12MP Sony IMX 486
1.25μm, f/2.2 Aperture +
5MP Samsung s5k5e8
1.12μm, f/2.0 Aperture
Front: 20MP Sony IMX 376
1.0μm, f/2.2 Aperture
As you can see especially the Sony IMX 376 camera is a proven camera used in Samsung (don't support their own camera???)
and other brands flagship phones. China version use the Samsung and OV sensors, although you can argue pixel size and
aperture slightly favorable here.
Real-life results most likely negligible with each version has it own pros n cons. So don't really matter, but I think likely M'sia
will get the China version.