There are two major subclasses for partner visa; this visa is broadly divided into two categories: Prospective Marriage visa and Partner visa. The type of visa for which you should apply depends on the type of relationship you are in.
Following are the types of relationship and the visas that correspond to them:
Intended marriage : Prospective Marriage visa
The prospective marriage 300 visa is granted to people who are engaged and want to get married to an Australian citizen, Australian permanent resident or eligible New Zealand citizen.
The visa allows applicant to stay in Australia for 9 months and apply for the Partner (subclass 820 and 801) visa within that period.
Married : Partner visa
The Partner (Provisional and Migrant visa) (subclass 309 and 100) allows those individuals to live in Australia who are a spouse or de facto partner of an either Australian citizen, permanent resident or eligible New Zealand citizen.
The provisional 309 visa is a temporary visa while the migrant 100 visa is a permanent. The temporary provisional 309 visa is granted first, which allows the applicant to stay in Australia for two years and apply for the migrant 100 visa within that duration.