Barnbougle and St. Andrews Beach are fairly different sites.
I know that all the courses in the "Cups" land on the Mornington Peninsula have compared themselves to links courses, and it's not just an outright lie like in Myrtle Beach, because the land is reasonably undulating and the conditions are windy. But it's not sand dunes, either; it's beautiful pasture land.
I tend to think of Sand Hills when I'm at St. Andrews Beach, but that's probably only because of the eerie similarity in walking both sites before construction and realizing how little earth had to be moved. St. Andrews Beach has tea trees on the ridges that separate the property, so it's got more "definition" to it than a links; and the ridges provide a predominance of elevated tees. You can see parts of other holes as you're walking it, but there's enough separation between them that you see only a piece of another fairway, and you're not sure which it is. It's a very roomy golf course.
Barnbougle is a real links, and one of the prettiest links sites I've seen anywhere. Sand dunes from start to finish, with marram grass and bushes to break it up a bit. The highest dune is about 50 feet above sea level; the lowest point is, literally, the beach. The holes are wilder and more rugged in nature than St. Andrews Beach ... or anything else I've seen in Australia. A comparison in the U.K.? Maybe the first few holes at Machrihanish, although there are some holes with bigger dunes than that.
Both of them are windy; Barnbougle is windier than St. Andrews Beach, and some days it's even windier than Lubbock or Bandon. Both courses are as wide as we could afford working with a budget, but there will be some lost balls at Barnbougle if you play badly, because the marram off the course is X. As for firm, like Ken Nice says in Bandon, it's really droughty there for a lot of the year ... I don't know how they could NOT wind up firm.