Also an Australian living in Austria (there’s a few of us), although not in Vienna.
Whenever I return to Australia (also mostly rural locations) the major difference I notice is bird life. There are so many more birds in Australia. Maybe they’re just noisier.
We put feeders out in our Austrian garden and do see plenty of small birds, as well as woodpeckers, crows and pigeons. However, in Australia there are lots of small birds too, like finches and wrens. As well as magpies, currawongs and the large noisy flocks of galahs and sulphur crested cockatoos. King parrots and rosellas regularly seen. Maybe it’s a regional Australia phenomenon, but it really stands out to me.
That's my memory of Sydney to. In Europe we sold every land parcel, reduced their habitat (forests) to 100m blocks, then 50m, then a public park with scientific studies used to justify that they'll be better off in the park... then they die. Turns out all scientific studies are paid out by promoters and everyone has a price.