If you want to become a member of Sam's Club, you need to issue either a credit card or a MasterCard card on the official website of Sam's Club. There are several differences between these two cards. Sam's club MasterCard has more advantages than a credit card. Firstly, it is possible to get 5% cashback on gas anywhere Mastercard is accepted. Also, if you are a member of Sam's Club, you can receive from 1% to 3% cashback from purchases with a MasterCard card. With a credit card, such opportunities are limited.