The raw numbers don’t seem to address gp’s point. Indian migration started earlier than Pakistani migration, so you’d expect more second+ generation migrants among Indians.
Edit: sorry, I didn’t realise you meant migrant flows. That is relevant, though it would still be better to control for generation.
https://m.economictimes.com/nri/migrate/indians-top-list-of-...
Perhaps one could argue that Indian migrants tend to be educational and work migrants, while Pakistani migrants tend to be family reunification migrants. But that again points back to the cultural reasons behind certain communities doing well, based on what they prioritize.