What is the difference in my search results when I search from Australia using:
And when I search from the same country using:
The first one is localized and not encrypted. The second one isn't localized, but it is SSL encrypted.
By "localized", I mean that the search results aren't prioritized depending upon your location. For example, searching "RAW" on google.co.in gives me this as the first result. From an India IP, encrypted.google.com gives me a link to WWE.
The "encrypted" part is much more interesting. What happens is that your connection is encrypted using SSL. What this does is that it prevents a third party from being able to eavesdrop/tamper with your connection. All data (except the URL) are sent in a form which only the receiver can read. So, all requests sent to Google can only be read by them, and all responses can only be read by you. An attacker cannot easily read the "conversation", let alone modify it. The only thing the attacker will see is the URLs you visited, and a bunch of stuff pertaining to the SSL "handshake" Which, if read, doesn't help the hacker much -- the beauty of public-private key encryption is that there is never any need to transmit a "password" and hope nobody sees it (all the handshake transmissions can be read easily, but they're hard to modify into something else that will be accepted by the reciever)
The main advantage of using SSL (in the case of Google) is that a hacker can't easily modify search results to point you to malicious sites. In the general case, it prevents all your personal data (emails, passwords, etc) from being read.
Of course, you can get the benefit of both worlds by just going to https://www.google.com.au/ .