What is the difference between MST and NFC technology?

With Samsung Pay, either NFC or MST technology can be used to make contactless transactions.  The key difference is that NFC requires an NFC-enabled card reader (newer technology available at fewer U.S. retailers) whereas MST works with many more types of card readers.  Because Samsung Pay incorporates both NFC and MST technologies, it works almost anywhere you can swipe or tap your card.