There are far more reputable sources of information on Universities than this one. You're better to look at the international rankings, like QS (and I can't remember what the other is—maybe New York Times or something if someone wants to confirm?). They use far more extensive sources of data, larger sample sizes and look at a lot more criteria. They also have an important reputation to uphold and a huge responsibility, so they're far more reliable as a result.
The other thing, just have a look at your Unis as well. The better Unis in Australia generally have no issue in telling you—even when you're a student there—every single second of the day what they're currently ranked.
It's also probably useful to note that Universities do have certain standards that they have to reach to give a degree, so you won't see a huge difference between them. A lot of the differences are about atmosphere and your class mates, which don't get me wrong, are hugely important!