According to 591, there are 2 sets of question pool. Depending on luck and location, one may encounter written review materials fully covered by 591, another is totally new question bank.
And probably this will continue towards end of AUG 2018. Beyond 30th AUG. v1.1 Evolving technology topics shall be introduced.
Candidates who plan to take any Expert-level written exam for qualification or recertification purposes on August 30, 2018 and beyond, should refer to the Evolving Technologies exam topics v1.1 or to the specific Expert-level certification exam topics which outline the changes in the minor revision.