A debit card is tied to a bank account, so the pre-authorization removes funds from the available balance immediately, whereas a pre-authorization on a credit card removes those funds from a credit line. Due to the fact that the check/debit card deals with available cash and not borrowed credit, the amount of the pre-authorization will not be available to you even though it has not been removed from your bank account.

Example: if a bank account has a $2000 balance and a $10 pre-authorization has been made only $1990 will be available for access. After the pre-authorization has been released, the $10 will once again be available.