[panick21_]

I mean one uses the main propellant to drive the turbine the other has a sodium permanganate/hydrogen peroxide. That seems to me a pretty significant difference in how the engine works.

To be fair, technically one could call both gas generators but its still significantly different.

[WalterBright]

I'm sorry, but picking a different source of hot gas to drive the turbopump is not a conceptual difference. Just like adding nitrous injection to your car doesn't make it a conceptually different engine.