I don't know. However top universities uses a calculation that does not reflect th course content and value to here in Australia. If you want to go overseas, then I guess UQ is a better choice. If you stay here, UNSW might be better. I'm not sure though and I'm only speculating.
On the official UNSW Chemical Engineering website, it says its course is 1st in Australia and 6th in the World. Of course, the organisation ranking the universities is different to the ones anomalousdecay posted.
UNSW without a doubt compared to UQ; Sydney vs Brisbane! blah!!! Also, rankings are not always accurate (whether UNSW is no 1 or not), but they do take a lot into account to come up with them. Also, for masters, PhD etc, you could always go elsewhere after getting a solid degree.