Currently, members get a 20% discount on meals at most (not all) the restaurants in the Swan/Dolphin resort. Most of the other food discounts are for lunch at selected resort and EPCOT table service restaurants and are 10%, not 20%.
There are some limited merchandise discounts at a few of the DD establishments, but as far as I know, none of the are 20%.
There is a complete list of current perks/benefits on the Members' website.
Best wishes -