More a curiosity question - I am not planning a trip or anything. But how does camping in Australia compare to camping in the USA?

I know they sell a lot of trailers/caravans, although many of them look more akin to rugged off road adventures than to the normal campgrounds one finds in the US. It seems there are a lot more tents and tent trailers than normal caravans. And do they have campgrounds with assigned sites and seperated by trees, etc? Or is it more European style where there is a big field and you go set up wherever you feel like?