Australia and New Zealand are very similar in a lot of ways, and have very close relationships. And New Zealand actually came very close to being part of Australia - Australia’s constitution actually includes provisions for New Zealand to join.
They are our brothers. But yes, not, the same thing.
One of the first things I saw while in the Sydney airport awaiting my flight to Adelaide, scratched in the men’s toilet stall wall:
Kiwis are bloody wankers!
I had no idea at the time what it meant.
Then about an hour later a guy asked me for a fag.
I seriously began to wonder what I had gotten myself into!