

I’ve played both 2016 and Eternal and finished both on Ultra Nightmare on both controller and KBM.
2016 was more of an artificial difficulty bump with enemies killing you very quickly and lots of restarting.
Eternal was more of a skill check. If you died it was because you weren’t good enough with the mechanics of the game. You should have been faster and been better with decision making.
Just my opinion.
I didn’t find Ultra Nightmare particularly easy. The life system doesn’t really change the actual gameplay difficulty.