Do we truly believe that on die memory has similar costs? I don't see how this is remotely possible but its going to take tear downs of both configurations to c

Do we truly believe that on die memory has similar costs? I don't see how this is remotely possible but its going to take tear downs of both configurations to check what is going on; as in are the 8gb units using chips which never had the circuitry or perhaps disabled by hardware and its still there?