When the Department of Home Affairs refuses your visa application, it means they've decided not to grant the visa you applied for. This usually happens because of documentation problems, insufficient funds, or doubts about your intentions.
Visa cancellation works differently. If you already hold a visa and receive a cancellation notice, it means the Department wants to terminate your existing visa. Common reasons include breaching visa conditions (like working in the wrong job), providing incorrect information in your application, or concerns about your character. You might receive a NOICC (Notice of Intention to Consider Cancellation) first, which gives you just 7 days to respond. Both refusals and cancellations can be challenged through proper legal channels, but success depends on addressing the specific issues raised and meeting strict deadlines.