This applies to any Apple Pay credit card, not just apple's card.
as others have said, your phone, watch and physical card each have a unique "card" number.
your phone or watch also generate unique codes for every transaction, So even if someone was able to snoop and pick up a transaction as it happened, the information they get can't be used again.
You have to manually activate payment, and authenticate before your device sends any data
the watch authenticates when you put it on, and stays that way until it's removed, you have to manually start the payment process with a double tap on the button. (it's why you can't use Apple Pay unless you have a passcode)
on the phone, you have to start a transaction by double tapping the button (or wave over an active payment terminal), and then use either Face or Touch ID to authenticate.
the magnetic stripe or the physical number printed on the card are much more likely to be the way scammers get ahold of your information.
See how your Apple Pay personal and payment information and transaction data is protected.
support.apple.com