In Indiana, the NREMT written is not required for state certification, we have our own state written.
I took both the state written and the NREMT. The state written had a lot more state-specific questions on it (obviously), things like ambulance operations, what color lights personal vehicles of EMTs are allowed to have, etc. There were a lot of questions about NIMS and other hazmat stuff. And of course a lot of scenario-based questions and medical questions. The state test was 200 questions, drawn randomly from a bank. Obviously this is the main difference between the state written and the NREMT, with the state test you will have 200 questions. Period. Not maybe 70 or maybe 120 or something in between.
I wouldn't say either test is "harder". The NREMT asked questions that got progressively more difficult, but it shut off at 70 questions. The state test asked questions that I found easy, and ones I found harder, but there were 200 questions and by the end I was seriously ready to be done with that test! I'm a fast test-taker, and that beast took me and hour and a half to complete.
So while they were a bit different, I wouldn't necessarily say one was 'harder' or 'easier' than the other.