I don't have personal experience from either, but from what i've heard/seen on the usyd website...
The first basic difference is that the BA/BSc you finish with two separate degrees whereas the other one is just one degree 'Bachelor of Liberal Arts and Sciences'.
Bachelor of Liberal Arts and Sciences:
- In first year you have to do 'Analytical Thinking' and 'Academic English' (2 subjects out of 8)
- You only major in either an arts field or a science field. Ie. you only have one major and you do a lesser number of subjects in the other area.
- you also have to do a couple more compulsory liberal stream subjects from the areas of rom the areas of Analytical Thinking, Communication, Ethics, Scientific Enquiry, Technological Literacy and Culture, Society and Global Citizenship.
Bachelor of Science/Bachelor of Arts
- no compulsory subjects as such (eg. no 'academic english'
- you get an arts major and a science major
If you don't know what you want to do (or you want to do both science and arts and may want to continue further study), I believe the Bachelor Arts/Bachelor of Sciences is a better broader degree and it also doesn't lock you into doing compulsory liberal studies subjects.
Whilst a liberal studies degree can come across as offering lots of choice etc, I had a friend that started doing a similar degree but ended up transferring out because although you can do lots of subjects, there are so many requirements that you have to follow that it can be frustrating ie. you may have to think out your major in better detail because you have to include the compulsory liberal studies subjects which may not be in your major area. In my mind, having to do a subject called 'Academic English' would also be a deterrent, but that's just my opinion...
(it sounds like a very boring kind of subject to do..)
However they are, in the end, quite similar. The benefit of the BA/BSC (which I find pretty amazing) is what would normally take 6 years (to get two degrees) you can do in 4, and if it was offered when I started university I may have considered it (I was unsure about whether I wanted to do science or arts).
Hopefully someone who does the degrees will be able to pipe up who actually does one of the degrees. However the only thing is I'm not sure how many people there will be- I believe the BA/BSC (4 years) only started 2010 or 2011 and the Bachelor of Liberal Arts and Sciences was a couple of years ago. The degrees in their current guises weren't around at usyd in 2007 when I started in any case (I think it was just called a Bachelor of Liberal Studies then and probably had different requirements).