There are three time zones in Australia spread over the width of Australia from Sydney to Perth and totalling 2hrs in difference, except for daylight saving time:
Eastern Standard Time (EST) - which includes New South Wales, Victoria, Queensland, Tasmania and the Australian Capital Territory
Central Standard Time (CST) - which includes South Australia and the Northern Territory
Western Standard Time (WST) - Western Australia.
CST is one half hour behind EST, while WST is two hours behind EST
Daylight saving is not observed in Queensland, the Northern Territory or Western Australia. Daylight Saving Time begins at 2am on the first Sunday in October, when clocks are put forward one hour. It ends at 2am (which is 3am Daylight Saving Time) on the first Sunday in April, when clocks are put back one hour.