There is tons more going on behind the scenes vs. a typical credit card.
For credit cards that are swiped the following happens:
- Your data is sent to an acquirer/payment processor who routes your data through the payments system for processing.
- The acquirer/processor sends the data to the payment brand (i.e. Visa, MasterCard, American Express, etc.) who then forwards it to the issuing bank.
- The issuing bank verifies that the card is legitimate, is not lost or stolen, and that the account has the appropriate amount of funds to cover the purchase.
- The issuer generates an authorization number and routes that number back to the card brand, agreeing to pay for the purchase on the cardholders behalf.
- The card brand forwards the authorization code back to the acquirer/processor.
- The acquirer/processor sends the authorization code to the merchant.
For Apple Pay (best guesses as no public info is known):
- Your credit card is first encrypted on your phone in form of a device ID. Only the issuing bank knows how to decrypt this number (not even VISA/MC can)
- The Terminal Communicates to your phone a challenge that is comprised of some sort of transaction info/id number
- After your finger print, your Phone responds with the device ID and an encrypted response to the challenge
- The acquirer/processor sends the data to the payment brand (i.e. Visa, MasterCard, American Express, etc.) who then forwards it to the issuing bank.
- The issuing bank verifies the encrypted challenge and generates an authorization number and routes that number back to the card brand, agreeing to pay for the purchase on the cardholders behalf.
- The card brand forwards the authorization code back to the acquirer/processor.
- The acquirer/processor sends the authorization code to the merchant.