How close is Apple Pay? Is there anything in an Apple Pay transaction identifying the customer (that can be correlated across purchases)?

I've heard good things but I have no idea about the details.

Edit: https://www.engadget.com/2014/10/02/apple-pay-an-in-depth-lo...

merchant sees NO account information but has the final four digits of the PAN [CC number] as an account identifier to use as a mechanism for tracking volume/activity per account