We don't speak English, we speak Australian.

Your stupid homework sheet is missing spelling differences btw. Be GLaD.
Also it assumes that each variety is the same across the whole country. While that is relatively true for Australia, you try telling me an american southerner sounds the same as their northern counterparts. xD
Syntax is a fairly standard thing between varieties (well, as long as you stick to standard English) and no one will be able to come up with much. One distinctive thing about Aussie English is that we end things with 'but' meaning like 'however'. Only example that springs to mind.
Phonological - I would go about that by thinking of the distinctive things in aussie english (which should be more familiar to you than to me by now), and then from that working backwards and going 'this is different'. xD
Only other thing I can think of is how according to america we live in Malbourne etc, and that we are slowly copying that

. Stuffed if I know vs British English, can't be bothered thinking there
