What you are seeing is the difference in exchange rates that your wallet provider is using compared to the BTC to AUD conversion we display on our webpage. On top of that, almost all wallet services have defaulted their displayed balance as USD. 

For example, if you are using Google exchange calculator, it will have its own conversion rate. All wallet services and our exchange use their unique exchange rates, so this is where that difference will come from. 

Therefore, you are basing your price on your wallet address' rate. It is using a different exchange rate from a completely different market. (Note if you bought it when the price was going up or down significantly, there will be a further difference in the price. 

The amount of bitcoins is always consistent, thus if you send those coins to a different wallet provider (minus the network transaction/ miner fee) it will show its own spot price depending on where they get there exchange rates from.)