Every person travelling to Australia, regardless for how long or short, must have a visa.
When you plan holidays in Australia, want to visit friends or family or plan to spend any time in Australia, you will need one of travel visas.
Deepens on your country of origin, past visa history (not only in Australia, but in commonwealth) it can be easy or not so easy process.
For high risk countries it may be long process with many documents required genuine intention to travel, found for travel, detailed itinerary etc
Work visa allow you to stay for specific period of time, but in most situations do not allow for any type of work.