The “regular” and “premium” label at the pump is misleading. The premium gas isn’t better. It’s just different. Unless your car specifically requires higher octane fuel, there is no benefit to paying for it. https://www.kbb.com/car-advice/gasoline-guide/

This may surprise you, but gas stations typically only have two grades of fuel stored in tanks. Mid-grade gas is mixed at the pump from the other two.

no, but made in same place with mostly same ingredients, just different ratio to hit higher octane (and in some cases some extra additives).

Also vary a bit between winter a summer, basically in winter they can get away with putting a bit more volatile compounds coz it's colder