Defnitely harder. Harder b/c they want you to see you need "help" and entice you to take their class. And harder b/c all of their practice tests are more difficult.
I really benefited from the Kaplan material--- I am a non-trad, out of school for 2+ yrs. I did well on my first try and since I was used to the super-hard Kaplan questions/practice tests, once I sat down at the real OAT and started answering questions.... it was the BEST feeling thinking, "wow, this is really not that bad!" Got that feeling w/in 5 mins. What a relief.