Why is the amount listed on my approved timesheet different to what has been deposited into my bank account?

The approved timesheet you get a copy of when your approver approves it is the full gross amount including superannuation and tax.  The amount that is deposited into your bank account has had superannuation and PAYG tax deducted from it.
You can see the full breakdown of how much was deducted for superannuation and tax on your payslip which can be found in the Reports Tab > Payment Advice.