Yeah I would agree that they are different, in my opinion, NBDE is much harder but it is curved so it is not hard to pass. I think you will miss a much larger % of questions but still get an okay score.
DAT isn't hard, I took the kaplan class for it and I don't remember how many hours of studying i put into it (prob a few weeks maybe 3 or 4 hrs a day), but didn't do great. Time limit on math is what killed me.
Studied 2 weeks (all day) for NBDE 1, and got a decent score.