Technically it's the same model, the ipatches were just updated to block Fusée Gelée.
To my understanding, it's the same motherboard, the ipatches were just updated as I've stated above.
With Fusée Gelée, firmware has nothing to do with it. If you buy refurbished from Nintendo(user refurbished would be the way to go, like on eBay) then you'll more than likely get a console that has updated ipatches. The only vulnerabilities that rely on firmwares are the TrustZoneHax(déjà vu and jamais vu) not yet released.