So, the user might have made a mistake, thinking there's a 9th edition. Alternatively, they might be referring to another source or a different book. I need to address that clarification in the article. First, I should explain that PMBOK hasn't reached the 9th edition as of now and that there's a possible confusion. Then, proceed to outline the real differences between the 6th and 7th editions, which are the most recent official publications.