Think of Area of Study as a module but in itself, everyone has to do the same topic. So for example Module A - comparative, I might study Gwen Harwood + Maestro whilst you may study Robert Frost + a different novel, same for Module B and Module C. However, Area of Study is a state-wide common study - so belonging for the past couple of years has been the AOS.
Since they have changed it to Discovery, you, I and the rest of NSW who completes their HSC in 2015 must study Discovery. Not quite a massive change to the syllabus since the aspects of Discovery and Belonging are in essence, the same. e.g. human nature, context, blah blah blah but it is something interesting to speculate on since its not often that an entire module is changed. However in saying so, because it is a new AOS; from what i have been told, markers tend to be more flexible since they understand that this is the first cohort to study this AOS... so work hard, attain good marks and sell your essays