The 143 and 173 parent visas are both subclass visa options for skilled workers who have been nominated by an Australian employer.
The 143 visa is a permanent residency visa, while the 173 visa is a provisional residency visa.
The main difference between the two visas is the timeframe in which holders are eligible to apply for citizenship.
Holders of the 143 visa can apply for citizenship after four years, while holders of the 173 visa must wait until they have held the visa for two years before applying.
In addition, the 173 visa allows holders to travel in and out of Australia more freely than the 143 visa.
As a result, it is generally considered to be a more attractive option for workers who are looking to eventually settle in Australia permanently.