An often underappreciated distinction between citizens and permanent residents is that if you are convicted of an offence you may be liable to forced removal if you are a non-citizen. [0]
There are cases in Australia of people who have spent nearly their entire life in the country, but never obtained citizenship, and who were deported for committing crimes, [1] including minor drug offences.
[0] https://communitylaw.org.nz/community-law-manual/not-rated/d...
[1] https://www.theguardian.com/australia-news/2021/mar/21/it-st...