What's the point of "Hard" difficulty in the newest expansion?

Like seriously, I was finishing 5th level on Hard diff when I realised I could've been playing it on Nightmare, as my health is capped at 50 anyway, and the power-ups appear to be increasing this cap further on Nightmare. I completely forgot the remaster changed the way Nightmare works. Is there anything I'm missing, or does it really look like devs' omission?