I have both books (both in hardcover and electronic)and started with the AIO (Shon Harris) book. I've read the first 750 pages. I've noticed things in the AIO that are not in the Official Guide (OG). For example Blueprints, AS/NZS 4360, etc. I'm sure there are things in the OG that are not in the AIO. Am I safe to assume that if it's not in the OG, it will not be tested?
Here's another example of material discussed in the AIO, but not addressed in the OG: