A .au direct domain name for businesses and individuals is more flexible as compared to registering a third-level com.au or net.au domain name. As long as the domain name has not been registered already, put on priority hold by another registrant or shows up in the registry’s reserved list, you can pick and choose the name that you want. It does not need to match the name of your business.
com.au and net.au are third-level domains for businesses registered with an ACN (through the Australian Securities and Investments Commission (ASIC)), businesses registered with an ABN (through the Australian Business Register (ABR)) and the respective state governments. org.au is a third-level domain that is reserved for use by charities and non-profit organisations.
There are however restrictions on registering 'closed second-level .au namespaces', such as state-owned namespaces (nsw.au, vic.au and so on) and special-purpose namespaces, such as edu.au, gov.au and csiro.au.