I just completed my GA BAK test. I managed to pass despite never having seen a load charts in my life and a basic understanding of aircraft performance charts & tables.
I trawled through the GA BAK syllabus and RA-Aus BAK syllabus and they are different.
Most notable difference is loading, balance and aircraft landing/take off requirements.
The GA BAK test I did consisted of two parts, Part A - 20 questions, General Knowledge stuff (aerodynamics, aeroplane general knowledge, etc), and Part B - 10 questions, Loading Charts (Alpha, Bravo and Charlie), and Aircraft Performance (Performance tables, charts). You are allowed 6 mistakes Part A and 3 mistakes Part B.
An example of loading question was, given all of the weights for fuel, pax, how much rear cargo weight can you have? Or, what is the maximum amount of fuel that can be carried with this load?
Performance questions related to how much takeoff/landing distance required given pressure height, slope, surface, wind, TOW, etc.