Hi amirsaf1.
The questions in GMAT Advanced range from medium to hard level, and the questions you'll see if you're scoring 700+ on the GMAT will all or almost all be medium and hard level questions. So, the difficulty of the questions in GMAT Advanced is comparable to the difficulty of the questions you'll see on the GMAT.
Regarding the exceptions in GMAT Advanced you mentioned, a key thing to understand is that the GMAT does tend to include questions different from those in the OG or on the official practice tests. In other words, there will be exceptions on the real GMAT as well. So, you need to get accustomed to seeing all kinds of different things going on, not just straightforward or common patterns.
In fact, one problem that people often run into when taking the GMAT is that the questions do things they aren't expecting and they don't know how to handle the questions.
So, I recommend practicing with as many different questions as you can to prepare to handle whatever the test presents.