There's not really a particular Australian food, I don't think - unless you're talking about kangaroo, emu, witchetty grubs and the like.
Oz is such a diverse country - and has taken influences from everywhere. Mod Oz food, at my favourite restaurant, Sean's Panaroma, has menu items influenced by just about everyone, and often features food from Sean's farm.
There's a couple of differences between Australian restaurants and US restaurants, from my very limited US experience.
Serves are smaller - plates are not filled to overflowing. A normal person can finish a meal - and not be knocked over by the calorie count.
There's usually an emphasis on fresh, local or sustainably sourced ingredients.
And the biggie for me - we pay our waitstaff - they're not reduced to almost begging - so tipping is not compulsory. And taxes are included in the menu price. So - the price on the menu is what it costs. Americans often complain about the expense of eating in Oz - but, as you don't need to consider a further 20-25% for taxes and tips, costs are really much the same. Tipping is the great bugbear of Australians in the US and Canada.
And for the Canadians - absolutely no
restaurant I've found in Australia, so far - has poutine on the menu!