Yes, everything we import from Russia is heavily downgraded.
In missiles, the seeker, propulsion system and fuel are different. As is the software. In radars, some modes are locked or simply not available, the range and resolution are lower. Sometimes even the internal electronics are different, with inferior TWT, inferior processing etc. All electronics are more or less inferior as well, except for COTS. These are basically the most important reasons why Western systems are superior to Russian exports.
With battle tanks as well, the engine, armour, gun, barrel, shells etc are all significantly inferior to what the Russian Army uses. At least half a generation behind.
But at the same time, with the downgrades, even the cost comes down, which makes them competitive.
India does get some leeway, especially when we pay for the development ourselves and is not used by Russian forces themselves, like the Su-30, when it was introduced. But if there's something being used by the Russian forces that we need, then you can only get a downgraded export model. They like to keep their secrets.
The Americans downgrade a lot of stuff as well, like the P-8I is downgraded, with some hardware removed, some software restricted. The Abrams also comes with downgraded armour and firepower, but that's because they don't want to export their DU-related stuff.
China is apparently the worst. At least America and Russia downgrade what they already operate. The Chinese make entirely new stuff for exports instead, and those are generally very bad even when compared to Russian stuff.