Credit card is a process of borrowing money first and then saving it, that is, spending it first and then repaying it. The longest interest-free period is 59 days, which makes you more flexible in financial management and free to enjoy credit. Of course, banks don't trade at a loss, they make money through merchants, and then you withdraw money, and you can't get it back without interest. If the repayment is not normal, you will be charged a high late fee.

A savings card is a deposit before consumption, that is, you have to deposit money in the card before you can swipe it. Cary has no money, so she can't spend it. She just puts cash in the Cary and spends it.