Prospective Marriage visa (subclass 300): this visa allows people to come to Australia to marry their prospective spouse. If you are granted this visa, you should marry your prospective spouse and apply for a Partner (subclasses 820 and 801) visa before your Prospective Marriage visa (subclass 300) expires.
Partner visa (subclasses 820/801 and 309/100): these visas allows the partner or spouse of an Australian citizen, Australian permanent resident or eligible New Zealand citizen to live in Australia. The temporary Partner visas — subclasses 820 and 309 — are granted first and let the person stay in Australia while the permanent Partner visas — subclasses 801 and 100 — are processed.