meaning behind the different paint schemes on Indian Su-30mki?

type 1: med grey body, light grey radome, black anti glare area around canopy

type 2: med grey body, light grey radome, no black anti glare area around canopy

type 3: light grey body, dark grey radome

do these different schemes represent different squadrons? different versions of the MKI? different builder as in HAL vs IAPO? whats the story behind the different paint used