The difference in value of two options, where the value of the one sold exceeds the value of the one purchased.
Credit: Money received in an account either from a deposit or a transaction that results in increasing the account's cash balance. A credit transaction is one in which the net sale proceeds are larger than the net buy proceeds (cost), thereby bringing money into the account.
Spread: A trade in which two related contracts/stocks/bonds/options are traded to exploit the relative difference in price change between the two. A trading strategy in which a trader offsets the purchase of one trading unit against another.