Am I right in presuming that you are currently casually employed?
If you are casually employed the semantic difference between "Rostered Stand-by" and "Reserve" is not relevant to you. This is because casual pilots by the very nature of the employment relationship are on reserve waiting to be called to work as and when they are needed by the employer.
The Air Pilots Award 2010 does not allow for payments to casual pilots who are not at work and just waiting to be called in. If the employer calls you in on the chance you might fly or do other duties then the relevant clauses of the Award will apply.
PM me if you need further clarification.
Have a good one!