There is not a difference in keeping NG's or Aussie's. Both prefer the same habitat, temp and food. Queensland frills come from a different climate then the Northern territory frills (I've been there and there is a huge difference), but are both found in similar habitats. NG frills extend to the tip of Queensland (which is a short distance from New Guinea). Some QL animals look exactly like NG animals and some NG animals look like QL animals. I bet its a huge mix of these guys.

The only thing you should consider when choosing between an aussie or a NG frill is whether or not you want a nicer colored animal that gets a little larger. Obviously NT frills are pretty, but there are red phase NG's out there that I have seen that look good too. There are also a lot of ugly looking aussie's. It depends on what you like and not what someone else thinks is "better".