Sony PS3 - confused about different versions?

Hi guys,im from Australia and looking into buying ps3's and selling on ebay Australia.
Just want to know about the different versions.I see some sites selling pal/jap as one versions,others saying one version for all countries,there are ntsc versions and pal versions etc,and hk versions with 110v to 250v input??.
So i want to know the diffrerent versions,and what one is the Australian version,with the Australian adapter and 240v input?
And what are the real difference in versions? Thanks guys!

Anyone also has anyone used a ntcs to pal converter?I saw some on a website,its suppose to change ntcs consoles to play pal?