To be able to answer this firstly you should understand us Australians like to do things differently and what makes complete sense to us generally is completely out of whack with the rest of the world.
But basically its both. We have 2 trophies that are pretty much regarded equal. That is the Premiers Plate that is awarded to the team that finishes with highest points after the regular season, which is not exactly home and away, but currently you play most teams 3 times each, I digress.
Then you have the championship, which is awarded to the team that wins the finals series and obviously the grand grand final. And its an endless debate on which trophy is more significant and until now there hasn't been a definitive answer.
To qualify for ASIA it's the Premiers Plate winner, but apart from that it depends who you ask.
I hope that clears it up.
Having said all that tonights game is huge for us as a club.