ok, from what I've read about and learnt if you aren't really sure about what you want to do (but have an idea of the general field you want to be in), then you should go to USyd, because it is much more flexible and as the years progress you begin to specialise as you become more aware of what you want to do. It is also easier to transfer between faculties should you change your mind about what you want to major in.
UNSW is far more specific and for those who know exactly what they want to major in, eg actuarial studies, or accounting etc. It is also very difficult to transfer between faculties and you are basically "locked into" your degree and the electives that are offered.
both have highly reputable degrees in areas such as commerce, science, so in effect what it really comes down to is your performance in your degree.
In terms of environment, if you don't mind studying in a manufacturing plant then go to UNSW but if you like an open spacious environment with a laid back feel go to USyd.
And as for extracurricular activities, USyd has more on offer.
And as for employment prospects and graduate salaries what it really comes down to is how good you are, not how good the uni is. And the fact that both USyd and UNSW are both prestigious means that they are in essence equal, and it comes down to the performance in your degree, how well you perform in the interview, and how well you can apply yourself to the work.
As for the good guides, I think they are a load, I question the accuracy of their information and their sources.