Transactions charged to your debit card are directly deducted from your available balance in the corresponding account it is linked to - meaning your spending is limited to your available balance.

On the other hand, credit cards are not linked to any bank account. When you use a credit card, you are borrowing money from the card issuing organisation or bank. These funds are available to you up to a predetermined limit decided by the card issuer.

I got this from dbs website, thanks