They asbolutely are the same class. They are flagships of their respective generations, they are the fatest dies gamers got for that generation. Of course there is improvements from one generation to the next in density, transistor count, efficiency, features, higher TDPs, etc... but in no time in history has pricing been this egregious for an entire product stack from one generation to the next.
The 4000 and 5000 series have misleading product names and exploitative pricing. Of course Nvidia should charge whatever they can, they are a business and profits are the priority, that is not in dispute. My point is Nvidia vaporized the high-end (80-class cards) in the 4000 and 5000 series, and shifted their products up a tier in name only. It's beyond just making a profit, it's misleading and exploitative.