What is the difference between PR, IRRV and citizenship in New Zealand?

After successfully applying for pr, you need to stay in immigration prison for two years, during which one year needs to stay for half a year, and two and a half years cannot be connected. After two years in prison, immigrants can apply for irrv permanent visa. Pr and irrv do not need to change their nationality. After the irrv application is successful, you can apply for New Zealand citizenship, obtain citizenship, and become a citizen after three years of residence.