There is one major difference between balance and available balance.
Your balance is the balance after transactions have cleared (posted to) your account.
Your "available balance" is the amount available in your account for use, at the moment. Your available balance may include pending debits or holds that have not yet cleared your account.
Online banking is a great tool to help you keep track of your balance and transaction history.
Online services include e-Statements, Mobile Check Deposit and Bill Pay, just to name a few.