Before I get too far into the thick of things, I'd also like to point out that I got this question significantly more at the beginning of my time here -- which, really, is slightly ironic. While I could give a general first impressions sort of answer (we, um, never say "amen" in the middle of a prayer), I think I'm actually in a much better position to comment now than I was then. Now of course no one is asking -- though finally if they do I'll simply be able to say, "yeah, tons of thoughts on that, check my blog!"
(This, incidentally, is not a random photo of a fake American church. It happens to be the fake American church that is part of my Grandfather's railroad village and that sits next to the fake American trees made, very creatively might I add, of grapevine.)
I think the biggest difference that I notice is that, by and large, most people in Australian churches are there because they are Christians and they want to be there. A higher percentage are what I'd classify "solid" Christians in Australian churches than American, where I tend to think there are a lot more "nominal" Christians whose faith you don't really see impacting their lives very much. While Australian Christians are far from perfect, they generally seem better at realizing how far from perfect they are and working to address sins in their lives.
Going hand in hand with this idea is the fact that Australian Christians are much more forthright in their conversations. "How'd you become a Christian?" "What challenged you most in the sermon tonight?" "What's been most encouraging for you spiritually lately?" and "What has God been teaching you recently?" are all common questions churchgoers must be prepared to answer -- at any time! While initially this struck me as forward and just a wee bit rude, I have come to really appreciate (usually!) the honesty and directness of Australian Christians -- I have found such questions to be very challenging, but have learned that they also strengthen my walk with God, as they show me areas I need to work on. I think American churches could cultivate deeper Christians if they followed suit and regularly asked such tough questions.
Discussing the sermon is a particularly salient point -- not only are listeners expected to stay awake and focused (no reading the bulletin notes or, worse, texting!); they are also expected (let me repeat: expected) to think about it, apply it to their lives, discuss it with others and, often, change an aspect of their lives because of it. While many American Christians would presumably agree, I find that the cultural expectation for these things to happen is lacking in most churches.
Another thing that surprised me at first in Australia is that everyone at church was expected (let me repeated: expected) to be in a connect group (i.e., Bible study, home group, care group, Bible fellowship group, whatever you'd like to call it). Sure there were a few on the fringes who didn't join, but they raised more than a few eyebrows. Compare that with American churches that are constantly striving to get 80% -- okay, 75% -- okay, 50% -- okay, if at least a solid handful are considering joining a Bible study that'll do.
Also, the Australian connect groups are not just connect groups -- they are given real responsibilities at church. For example, they are rostered on schedules for welcoming, preparing "supper" (i.e., coffee hour), cleaning up after church, helping with various outreach events, etc. While you could argue the "20% doing 80% of the work" rule still holds true, I don't think the discrepancy is as large in Australian churches.
So, between always being prepared to give an answer for the sermon you heard and being expected to give a day for the connect group you're in, I think Australian churches really do foster spiritual growth in a way the many American churches are lacking.
Interestingly, on the flip side, Australian Christians also engage in many behaviors that would raise many American Christian eyebrows. I find their language shocking at times (you just said what?! in a church!?), and the concept of modesty is rarely touched (ha!) upon. Almost no books or movies would incur a social taboo (regardless of whether or not a Calvin understanding of discernment took place). They drink tons more beer, often head to the pub after church and pretty much always supply alcohol in social gatherings. And, while they may agree with the American political right in terms of issues such as abortion, they're much less likely to share the same politics (which, yes, they usually know more about than most Americans do). They're more concerned with the environment than most midwestern Christians, and generally more politically liberal. And not only that, they don't have adult Sunday school.
At the same time, though, they hold fast to the Bible as the true Word of God, and place significant emphasis on the concept of "teaching" -- which is often one of the big deciding factors for church shopping Australians: is the teaching solid? Most agree that Sydney is a hotspot for excellent teaching (sound doctrine, etc.), which allows even the soundest of Christians to pick their parish of choice based on secondary factors, such as the hotness of the single population (which, see notes at modesty, is not difficult to ascertain).
While the standard of teaching at Sydney churches is generally very high, there is some concern that the truth is going out, but without very much love. The Sydney diocese has a reputation for being very conservative and sometimes unlovingly exclusive. Also, some seminary graduates are, though intelligent, perhaps better suited for occupations other than ministry -- while they can think and reason well, they sometimes, simply put, lack social skills or awareness, particularly to the level necessary for a potential pastor to have.
Perhaps because of this, or perhaps for other reasons, I have found a lot less idolizing of pastors in Australian churches. I remember visiting numerous American churches only to be told, "Oh, you've got to come back next week and hear the real guy preach. This one was okay, but just wait till you hear Chris!" This really rather got on my nerves, so imagine my joyful amazement when my church's senior pastor traveled overseas for a couple weeks (multiple sermons!!) and no one batted an eyelash! I was shocked, though in a good way. No one commented that he wasn't there, no one chatted that this sermon wasn't quite up to snuff and everything just ran smoothly. It was great. Of course, it was also great to have him back, but the fact that the glory was going to God instead of one human is what made all the difference.
I think my church does a good job of allowing this to happen because the preaching duties are shared -- yes, our senior pastor does the majority of the preaching, but it is also shared by various other pastors and student ministers. I've probably heard at least half a dozen people speak multiple times. Also, the service "emcee" is a varied role as well, with many different people wearing that hat. Thus, it is entirely possible to go through an entire service up to the sermon -- or even, get this, an entire service -- without seeing the senior pastor up front.
The subject of church retreats is an interesting one: in American churches, retreats are where it all comes out. They're the time to share your testimony, how God is working in your life, what sins you're struggling with, why your life is falling apart and how moved you are by God's presence -- in short, all the things Australian Christians question each other about on a weekly (or, if they're good and going to connect groups, twice weekly) basis. This leaves Australian Christians conveniently free to relax and enjoy their retreats with very little thought of God in their free time, which can then instead be spent playing sports, tanning in bikinis on the beach, drinking down at the pub or making slightly off-color jokes around the bonfire, all while American Christians are passing the second round of Kleenex and coke.
These, then, are the major differences I've picked up on between American and Australian churches (thanks for asking). I'll leave you simply with the "little" things -- the first impression stuff, the things I noticed right away and that stand out the most to visitors, but don't really have all that much bearing on anything, and which I always felt constituted a pretty weak answer to the question of how American and Australian churches differ. Thank goodness I've finally come up with something else!
--Americans almost always go to church on Sunday morning. There often are evening services, but these are usually either seen as "in addition to" or "for teens." My Sydney based church has full-fledged services Saturday nights (yay!!), Sunday mornings (2) and Sunday evenings (2). Interestingly, people are encouraged to pick one service and stick with it -- drifting between two is another Australian eyebrow raiser!
--Australians all sit down after the end of their service.
--Pronunciation of certain words, particularly "Isaiah" and "One John" instead of "First John."
--Australians listen to a "Bible talk" instead of a "sermon." Similarly, they hear "talks" at evangelistic events, weekend retreats and Christian conferences.
--My church doesn't give bulletins with the order of service, though I've been told other churches do.
--Australian Christian children stay in a "creche" instead of a "nursery" which is made up of people who do not go to that particular service -- instead of taking anyone away from their service, regulars of other services are asked to step in come (gasp!) twice in a weekend to support those at other services. Thus, most Kids' Church leaders come Sunday mornings to help out, but actually attend evening services.
--My church doesn't actually have members, though presumably other churches do.
--Most Australian churches don't double as basketball courts.