When you live in a culture different from what you grew up in, it's not big things you realize are different, but subtle differences which come up and bang you on the face, leaving an expression that generally leaves the natives shaking their heads.
In my case, I find the differences to be generally amusing.
For example, living here is like living three years in the past. Technology isn't cutting-edge. The Kindle debuted in August and it was a Big Deal. Most Australians will never know what the white, first gen ones were like, because the ones being advertised are the second gen. And supposedly the current, third gen Kindles are here, but I haven't seen them, so my source may be misinformed.
I bought the new Kindle for cheaper than buying here would cost me, even with shipping.
Another funny thing - watching TV shows which are a season or two behind the US. Now to be fair, many are current (such as Big Bang Theory), but the ones which are a season behind are amusing. I feel like a time traveler who can't tell her culture the secrets of the future.
Experiencing November as summer is unsettling, especially since the Christmas decorations are up. Tinsel everywhere, and no arguing about the propriety of baby Jesus on public buildings.
Sometimes the differences are quite annoying, such as paying out the nose for internet. Blazing fast speed here is ADSL2, which reaches a whopping 1.2meg download speed.
*twirls finger*
At some point, I'm going to write a post about actual Australianisms, which is the slang used here, so stay tuned.