TAFE is a technical school, with courses designed specifically for jobs, where as University is traditionally a place to study subjects for the sake of studying them as opposed to getting job qualifications. A university's main focus is research, not Job training, whereas TAFE is a pure job training centre. That's why you wouldn't get things like Social Sciences (at least in depth) at TAFE, but you get things like Accounting.
Of course now days University does offer courses that relate to specific careers (Accounting, Law for example), and this sort of blurs the distinction a bit. I think most people see University as a job training centre because most people want to get jobs, which is fair enough, but it can be a little innaccurate. Yes universities do train people for jobs, but that's one slice of a much bigger pie.