Gasoline is all the same. Except that regular can have up to 5% other stuff that burns (kero-aero, diesel, transmix). Premium is protected, no stray products added. These products are pipeline transmix - the pipelines pump many more refined products than just gasoline.
Oh, the truck that delivers to the station, at the truck loading rack he adds a quart or so of the brand name's latest advertised stuff. Techron, Z7, zippidy do, whatever.
I buy the cheapest gas and every 10 or 20 K miles add some Techron (detergent) concentrate to the gas. Rislone/Marvel and most similar stuff is a kerosene and light weight oil with a nice perfume added. They work, a little bit.