The biggest improvement with Apple Pay is that NO credit card information is actually transmitted to the merchant in the transaction.  

Apple Pay uses tokenization technology to provide a one-time payment number and dynamic code that changes with each purchase. 

In its simplest form Apple Pay works by combining different physical and software elements to keep transactions secure: the Passbook app to store sensitive information, the NFC radio, Touch ID (effectively your fingerprint scan) and a Secure Element chip. All a customer needs to do is enter their card details on your Apple device and they are converted through tokenization (supported by Amex, Visa and MasterCard standards for tokenization announced in October 2013). 

To store a debit/credit card on Passbook, customers simply take a photo of it using the iPhone camera – numbers side up – and Apple will then verify the card and store its details on the Secure Element chip. Alternatively, they can enter the numbers the old-fashioned way.   From then on, the TouchID is all that is needed to complete a checkout.