Earlier quoted context omitted.
That's what I was thinking, which means you're not actually giving Apple your CC number.
My experience is that you can start the process by entering your credit card details, or use your camera to try fill them in for you. Apple then checks if your card issuer has ApplePay enabled and if so provisions a “virtual” card which is what is stored on the device’s Secure Enclave. I also just checked my banking app quickly which can initiate the adding of the card to wallet, showing the wallet’s add card screen…
IIRC it's not exactly the same. One user-facing example where things are different is that contactless payments with a regular credit card have a 50 € maximum. If there is a limit when paying with the iPhone, it's much higher.
I also seem to recall that the merchant's payment contract must support this, but I'll have to confirm with a colleague. Although Apple Pay support is very common where I live, it did happen a few times that some restaurant's terminal accepted VISA contactless but not Apple Pay.
I've also had a situation where my CC is set up to not allow payments outside my country. Payment with Apple Pay was denied as being "out of country", whereas the physical card worked fine. The store is from a big national chain, in the heart of the capital city.