Yep, they are indeed different exams.
The BAK comes first and some would say it can be harder. It is usually set by the flying school and contains localised questions. The BAK is required to be able to obtain your GFPT which will enable you to fly with passengers in the training area of your flying school.
The PPL exam is standard across the board and is set by CASA. It is required usually before your final flight test for the issue of your PPL. I hope that answers your question and good luck.