I’ll refer you to this gem of a summary from Raul, developer and (I believe) owner of Flight Sim Reborn.
In short, it’s a huge range - something could technically be “2024 native” and be almost indistinguishable from its 2020 version to the average user. It could also be a complete ground-up rebuild of the aircraft that took tens of thousands of development hours and brings with it dozens, if not hundreds, of new features to the product that are platform-specific.
And just as there’s no legally defensible definition of “2024 native” there’s even less of one for “study level.” It’s purely a marketing term with no true quantifiable (or at least universally agreed-upon) meaning, so I would not put much stock in it, especially when it’s said by the creators of the product themselves.