Who is right in the Abbott-versus-Turnbull policy wars?

“It’s very easy for me to campaign for the election of the Turnbull government,” Tony Abbott declared on Monday, because “fundamentally the Turnbull government is seeking election on the record of the Abbott government”.

It was the latest provocative shot – delivered in a Sky interview from London – in the legacy war Abbott is waging. It was also a warning light for the government’s election campaign, when everything Abbott says will be monitored for signs of division.

Abbott named the record as including stopping the boats, the free trade agreements, the strong national security policy, and the workplace relations policy. He played down Turnbull initiatives as “a few other things that have been done over the last six months”.

The spurned former prime minister’s claim cuts deep because it taps into criticism of Malcolm Turnbull that’s coming from very non-Abbott quarters – those disappointed he has not delivered more on his known beliefs, on climate change and same-sex marriage, and those who say he simply hasn’t done much at all.

The ABC’s Leigh Sales put it bluntly to Turnbull on Monday – before the Abbott interview. There had been very little policy change, she said, so “what was the point of knifing Tony Abbott?”

Turnbull, who likes to portray himself as taking issues “out of the long grass”, rejected that as “quite untrue”. He pointed to Senate voting reform (which Abbott says he would have reached), cities policy, support for public transport, media reform and innovation policy. In subsequent comments he added strengthening competition policy.

“Between Tony and myself … there is continuity. Of course, I was part of his government, part of his cabinet – but there is also a great deal of change,” Turnbull said.

Pursued on Tuesday about Abbott’s comments, Turnbull struck to hurt, talking down an achievement of which Abbott is most proud.

Turnbull said he gave full credit to Abbott for stopping the boats but then noted the Abbott government’s policy “was to reinstate the policy of the Howard government of which we were both cabinet ministers. When I was opposition leader before Tony became leader I strongly opposed Rudd’s dismantling of the Howard policy.

“So whether it is Howard as leader of the Liberal Party, Abbott or Turnbull, we’ve had the same policy on border protection. So this is not something that was invented by Tony Abbott – this has been a continuum and we will maintain the same policy commitment.”

Turnbull stresses the voters will be looking towards the future in the election – in other words, he’s suggesting it won’t be so much about record.

Beyond that, who is right in this dog fight about policy paternity?

Both Abbott and Turnbull can draw on some points to suit their cases.

In Turnbull’s reversion this week to industrial relations as the trigger for a prospective double dissolution, he is firmly on Abbott ground. Abbott set up the trade union royal commission and would have used its report to the hilt in an election campaign.

For a while, it appeared that Turnbull would be very different from Abbott on tax reform – much bolder and more adventurous. But then the GST went off the table and the gap narrowed, although judgement about Turnbull’s approach must await the May 3 budget’s tax package.

Abbott is now going out of his way to articulate an anti-reform stand on tax, condemning Labor’s “five new or increased taxes” – changes to negative gearing, capital gains and superannuation, a hit on “workers having a smoko”, and a “carbon tax”.

This is mischief. Abbott knows the budget will contain reform of superannuation – which he refused to touch – and is expected to increase the tax on cigarettes.

Turnbull pledged to the conservative Liberals and the Nationals not to change the Direct Action climate change policy. But there have been more progressive approaches, including to renewables and to the Clean Energy Finance Corporation, which the Abbott government had wanted to scrap.

On climate, Turnbull goes to the election in a corset he agreed to wear; after a win he would be freer to pursue his own views, unless he restricts his options during the campaign.

On same-sex marriage Turnbull is taking Abbott’s plebiscite policy to the people. There is a very big difference, however. Turnbull wants the plebiscite to succeed and can be expected to throw his weight behind the yes case; Abbott wants it to fail and would have put a dead hand on it.

The areas Turnbull listed are significant points of differentiation. And as policy initiatives are rolled out for the campaign, there will obviously be a lot more of what Turnbull calls “signatures of my leadership”.

Many of the key differences between the two administrations, however, are in tone, emphasis, detail and priorities.

For example national security policies remain the same but Turnbull’s voice is inclusive where Abbott’s was not. Abbott was gung ho on commitments abroad, Turnbull is cautious. The strategic thrust of the defence white paper would have been similar whoever delivered it, but Turnbull tied it firmly into innovation.

On the economy, Turnbull is developing a distinctive narrative about transitioning to a new economy.

Turnbull, perhaps by necessity, is more ready to acknowledge what went before him than Abbott is willing to concede what has come after him. Abbott’s unreconciled mood is dangerous for the campaign, as Turnbull knows.

Will Abbott be a plus or minus for you in the election campaign?, 3AW’s Neil Mitchell asked Turnbull on Tuesday. “It depends what he says, frankly,” Turnbull said. “Whether it’s a plus or a minus depends entirely on the nature of his contribution.”

A statement of the obvious at one level - but also a blunt admission from Turnbull of the great uncertainty Abbott poses for the Liberals in the election run-up.