I felt in OG Quantitative, all of the questions are similarly on the easy side, EXCEPT for the last 15 or so in each entire section. The last few DS were particularly brutal, I got less than 1/2 right on those the first time through. These last few ARE representative of the difficulty of the highest level real GMAT, imho. The real GMAT does not save the hardest for last, it spreads them out and certainly you will see some of the harder questions in the first 15.
For verbal, I felt the hard questions were scattered throughout, not concentrated at the end at all.