We were on Voyager of the Seas in October 2006 for a 7-night Mediterranean cruise. There was a greater mix of nationalities, but generally it seemed much the same to us. I expect you won't notice much of a difference.
We did notice a bit of a "nicer attire" each evening, but I think that had more to do with ports, weather, itinerary. European cruises are not as casual as Caribbean. We've not experienced an Australian itinerary or South pacific.
All in all, a GREAT experience on our Med cruise. I'm sure you'll enjoy yours!