I guess what I'm asking though is can the reader differentiate between the two? My understanding is that Apple sends a one-time use card number to the reader, s

I guess what I'm asking though is can the reader differentiate between the two? My understanding is that Apple sends a one-time use card number to the reader, so maybe it's possible for the software could run some variation of a Luhn check or whatever to figure out if it's an Apple generated number, but failing that, isn't the communication protocol between the phone and the payment terminal standardized? In other words, can a merchant reasonably accept Apple Pay without accepting Google Wallet? I'd be surprised if they could, but I don't really know -- I'm legitimately asking. A quick bit of Google indicates ISO14443 and EMV as the relevant protocols, but I'm not 100% sure there's not some incompatible extension thing going on that would preclude treating different companies' implementations the same.