Two ETFs tracking same index give different returns

Didn’t really understand the question. But the right way to buy an ETF is to use a limit order at the iNAVs shown on the AMCs sites.

You can in multiple of the creation units - which is about Rs 50 lakh. Not less than that.

AMC appoints market makers and if they see an opportunity when the price and NAVs are out of whack, they’ll step in arbitrage the price away. But maybe it’s harder during volatile markets.