The main difference in my opinion is the additional value a competent travel consultant can add in terms of recommending the best suited room/suite category by knowing the clients' stay history/preferences/etc., by following up with the hotel, building/maintaining good relationships with the hotel/management.

The published benefits are indeed very similar (if not identical) across the various programs (the vast majority of properties are affiliated with several), and a good travel consultant can often get in touch with the hotels and get the amenities matched in case there's a discrepancy.