both uni's are really different...
the usyd atmosphere is very academically orientated. SOME people there are snobby.. but not all are. on a typical day there are thousands of people, so much more than mq.
i think the MQ atmosphere is friendlier and people arn't as obsessed with getting top marks.. at MQ it 'seems' people are happy as long as they pass.. which i guess everyone would be content with..
the usyd degree structures are very flexible, most so than at mq, but then again it depends on the degree. mq's degrees are really structure and not as flexible in that you gotta pick specific programs/patterns of study. where as at usyd, depending on your degree, you pick a major and do the required units for that major.
usyd has way more resources. the mq library sucks. the computer equipment is pretty much the same but the usyd network is much better because you only need to know 1 password and user name, not like mq where they give you so many.
the mq campus is much GREENER and its not as big as usyd. usyd is like a suburb with streets. i like the mq campus better because it means less walking and its not so hilly.
the tutors at usyd are much friendlier at usyd and much more approachable. at mq, they basically get straight to the work in the first tute/lab/prac.
i transferred to mq because of their internal transfer policy, sad to admit it i know. i didn't get my d average to be able to trasnfer within usyd plus i hated my course.
those are just generalisations but if you got any specific questions let me know...