Equal partners, but not too equal
Living alongside the Australians offers many advantages for New Zealand, from defence to tourism. We have an automatic right to work there, and an automatic right to residency - as they do here.
Currently, though, a clear imbalance exists in the relationship, and it's getting worse.
Australian Prime Minister Tony Abbott has made it clear that Kiwis working and living in Australia will continue to pay taxes there without receiving the welfare benefits that we give to Australians living here.
At a joint press conference with John Key in Sydney last month, Abbott told New Zealanders to be "lifters, not leaners".
Thanks for the advice, Tony.
Last week offered a striking example of Australia acting in conflict with us on the world stage.
The Sydney Morning Herald published documents showing that Australia used diplomatic pressure to block an attempt led by New Zealand - and other countries - to pass a United Nations resolution that had sought to ensure that nuclear weapons could never be used again, in any circumstances.
Last October, it seems, we had asked Australia to endorse a joint United Nations statement along those lines. The Aussies refused.
In their view, such bans would be mere window dressing, and would divert attention from what Australian Foreign Affairs Minister Julie Bishop called the "real work" of nuclear disarmament.
Not that Australia has been at the forefront of that, either.
Key seemed relaxed about being rebuffed.
It was different for Australians, Key indicated: they sell uranium and they're in Anzus.
"It's just one of those things where they come from a slightly different perspective," he said.
Indeed. Being in Anzus means being in a defence pact with the United States, which isn't inclined to abandon nuclear deterrence, given its role during the Cold War.
By and large, the incident has been an occasion for self- congratulation on New Zealand's part about our virtuous anti- nuclear stance, amid a lot of tongue-clucking about the Australians.
In fact, there is little reason for New Zealand to feel smug. When it has suited our diplomatic preferences to do so, we have been just as ready to reject United Nations calls for nuclear disarmament.
Only a few years ago, when there was a United Nations move to declare the volatile Middle East a nuclear-free zone, New Zealand voted against the resolution, mainly on the grounds that the draft resolution could be seen as a criticism of Israel, the region's only current nuclear power.
Alongside our differences on the nuclear issue, there is a palpable hardening in the Aussie treatment of New Zealanders resident there.
Reportedly, New Zealand students attending universities in New South Wales have been barred from public transport concessions.
A draft Social Security bill before the Australian Senate will even affect Kiwis who shifted across the Tasman before February 2001 - the date when our access to their welfare entitlements was changed.
From now on, all Kiwis who have been resident in Australia (and paying taxes for decades) face being made ineligible for cash incentives being offered to the long-term unemployed to relocate.
So far, there's been no sign of a tit-for-tat response.
For now at least, Social Development Minister Paula Bennett seems far more willing to be tough on Kiwis applying for welfare support, than on Australians doing the same at our expense.