There are three versions of Membership Rewards:

Membership Rewards First, offered with Platinum and Centurion charge cards. First includes redemption choices not included in the other versions.

Membership Rewards, the standard program offered with Green and Gold charge cards.

Membership Rewards Express, offered with credit cards, such as Blue, Optima, The Knot, The Nest and some business credit cards. Express points cannot be transferred to airline or hotel programs, unless linked to a charge card that participates in one of the higher level programs.

I do not know if there is any difference in the Express redemption values if used for gift cards or merchandise.