Can I make a payment with my discover card

If you mean for your Apple Card, then no, that would be considered a cash advance, which the Apple Card doesn’t support. You can only pay your Apple Card balance from your Apple Cash, your bank account, or your debit card.

No. Paying credit card debt with another credit card is not allowed, may be considered fraud or illegal in some places.

You can only do that through debt refinancing or balance transfer where you move your credit debt from one credit institution or bank to another and restructure your payments on said debt.

Are you referring to making a payment to your Apple Card with a Discover Card? If this is your question, then the answer is NO. You cannot make a payment for a credit with another credit card.

Axel F.