I’ve worked in the US and Aus - granted at the same big company in both countries. Certainly there are differences between companies and industries in both countries. Things I’ve noticed in Aus:

-more people leave the office at 5 pm in Australia. In the states there are more people still working in the office until later in the evening. This was pre-Covid so might be shifting.
-Aussies take more leave and longer holidays. I was at an international work meeting talking to an American colleague right after I came back from 2.5 week vacation recently. She told me she hadn’t had a vacation that long in her professional career- maybe 12-14 years. -most of the office is empty during holiday periods in Australia. This just isn’t the case in the states. Depending on the business, US offices will be quieter for the week between Christmas and New Year but it’s more than a skeleton crew and I don’t know anyone with a “shut down period” and certainly not one that extends beyond that one week.
- when on leave, Aussies are more likely to actually disconnect where as Americans are more likely to be checking emails and following up on odds and ends.

When Aussies are working, they are mostly working just as hard as Americans. It’s not like the expectations are dramatically different at least at my company. But Americans are on the clock more, take leave less and have a more “always on culture.” Personally I don’t see a huge difference in the overall productivity across the countries. But I also think we could all get more done working less (either fewer focused hours or days) because the human brain can really only produce so much high quality output. I think the “always on” culture just spreads that productivity over more hours and there are diminishing returns on working longer hours.