The difference between credit and debit, relating to a bank card, is that credit allows a purchase without immediate funds based on the customer's trusted and proven ability to pay, while debit is an actual debt recorded in an account, as defined by Dictionary. In bookkeeping and accounting, a credit is a payment to an account, and a debit is a debt on an account, according to Bookkeeping Basics.
When using a bank card, the cost of a purchase made on credit is not immediately removed from a person's bank account. Instead, to delay the payment, a credit purchase uses a grace period called "float." According to CreditCards.com, float is the time difference between the occurrence of a transaction and when the transaction is posted on an account. Float time is usually only one or two days. Conversely, a debit transaction using the same bank card posts to the account immediately, and it functions identically to paying cash directly from the bank account.
As the term "credit" relates to accounting, Bookkeeping Basics explains that the credit column is the right side of a ledger, and it records the payments to an account. The debit column is on the left side, and it records the expenses and debts to an account.