Owen Smith is attempting to unseat Jeremy Corbyn in a Labour leadership contest. There is a lot of overlap between the two in terms of policy - such as tackling inequality and making the rich pay more tax - but there are also some key differences.
Jeremy Corbyn is a lifelong member of the Campaign for Nuclear Disarmament and a supporter of unilateral disarmament. He believes Britain should get rid of its nuclear weapons, as part of a move towards a "nuclear-free world", and is firmly opposed to the renewal of the country's Trident nuclear weapons. Labour's official policy is to renew Trident, although that is currently under review.
Owen Smith says he "wants to rid the world" of nuclear weapons but thinks it can only be achieved through negotiation with other nuclear states - not by unilateral disarmament. He says "the country wants the Labour Party to be serious" about security.
One of Theresa May's first acts as prime minister in July was to hold a parliamentary vote on Trident renewal. Owen Smith was among 140 Labour MPs to vote with the government to renew Britain's fleet of submarines armed with Trident nuclear warheads. Jeremy Corbyn voted against the motion, along with 46 other Labour MPs.
Mr Corbyn has consistently voted against the use of UK military forces in combat, including the Iraq war in 2003.
Mr Smith was not in Parliament when the Iraq conflict started but speaking to the Wales Online website in 2006, he said he did not know whether he would have voted for military action.
He said: "I thought at the time the tradition of the Labour Party and the tradition of left-wing engagement to remove dictators was a noble, valuable tradition, and one that in South Wales, from the Spanish Civil War onwards, we have recognised and played a part in."
More recently Mr Smith has said going to war in Iraq was wrong.
Both candidates were opposed to extending UK air strikes against so-called Islamic State to Syria in 2015.
A major disagreement emerged in a BBC hustings event when Owen Smith suggested that so-called Islamic State would eventually have to be brought into peace talks if there was to be a settlement to Syria's civil war.
He said: "At some point, for us to resolve this, we will need to get people round the table."
Asked the same question, Jeremy Corbyn said: "They are not going to be round the table. No."
Afterwards Mr Smith's campaign said he was "clear" there should be no negotiation with IS - or Daesh - "until they renounce violence, cease all acts of terror and commit themselves to a peaceful settlement".
Differences have also emerged between the two men on over Britain's role in Nato. Mr Smith has said he would would provide military help to an ally if it was attacked by Russia, in line with Nato treaties, but Mr Corbyn would not commit to such a policy.
Second EU referendum
Owen Smith backs a second EU referendum, if the Brexit deal reached with the rest of the EU is bad for workers rights and the NHS. If he wins, he says he will try to stop Prime Minister Theresa May triggering official EU exit talks unless she offers a referendum on the final Brexit deal or agrees to call a general election to approve it.
Jeremy Corbyn says he wishes the UK had voted to remain in the EU and insists he did "his best" in the campaign despite claims by Mr Smith and other Labour MPs that he made a half-hearted effort.
But he has ruled out holding a second referendum saying "you have to respect the decision people made". Mr Corbyn's campaign says Mr Smith's second referendum plan would be "deeply unpopular" and cost Labour "an awful lot of seats".
Jeremy Corbyn promises to abolish tuition fees and bring back student maintenance grants, arguing that education is a "collective good that benefits all of us". He wants to introduce a National Education Service, providing free opportunities for lifelong learning.
Meanwhile, Owen Smith says he favours a graduate tax rather than tuition fees paid for by student borrowing. He would also end charitable status for private schools and use the money raised to pay for new Sure Start centres.
The economy, jobs and pay
Jeremy Corbyn promises a £500bn boost to the economy, including investment in infrastructure, manufacturing and new industries.
Owen Smith pledges an investment fund of £200bn - a "British New Deal" - to "rebuild Britain".
On housebuilding, Corbyn is aiming for one million new homes over five years while Owen Smith promises 1.5 million over the same period.
Mr Corbyn says any business with more than 21 members of staff would be forced to publish pay audits in an attempt to crack down on discriminatory wage practices. He has said he wants two million new skilled manufacturing jobs, the abolition of "zero hours" contracts and a "full" living wage, starting with care workers.
Owen Smith would bring back wage councils, whereby employers and workers' representatives sit on boards to establish pay rates. He also proposes the abolition of "zero hours" contracts and their replacement with minimum guaranteed working hours. He also proposes workers be placed on company remuneration committees and an end to the public sector pay freeze. He is calling for a "real living wage".
Both men want to renationalise the railways.
The candidates are united in their desire to reintroduce a 50p top rate of income tax for earnings over £150,000.
Jeremy Corbyn has said the government should consider imposing "direct rule" on British overseas territories and dependencies if they do not comply with UK tax law and has criticised government cuts to corporation tax.
Owen Smith has said Labour has been "too timid" about taxation and calls for a more "progressive" system. In addition to a 50p tax rate, he would introduce a 15% tax on wealth for the richest 1% - raising £2.8bn a year. He would also reverse cuts to inheritance tax and corporation tax and raise capital gains tax from its current 20% rate.
The future of the NHS has been a key battleground in the contest. Owen Smith's campaign was initially dogged by questions about NHS privatisation. In his previous job as a lobbyist for US drugs giant Pfizer, he had commented on a report exploring the greater use of private providers, saying: "We believe that choice is a good thing."
Mr Smith insisted he had always been committed to a "100% publicly-owned NHS free at the point of use" and accused Jeremy Corbyn of using his former job as "a stick with which to beat me".
At his campaign launch Mr Corbyn had said he hoped Mr Smith would agree with him that the NHS should be free at the point of use, adding it "should be run by publicly-employed workers working for the NHS not for private contractors, and medical research shouldn't be farmed out to big pharmaceutical companies like Pfizer".
Mr Smith said he was not ashamed to have worked for companies that make medicines to treat cancer, diabetes and asthma. He added: "The NHS doesn't make medicines. It helps with research, but it can't make medicines.
"It would be physically impossible for the NHS to be able to trial medicines around the world, so of course we will always rely on external forces, companies essentially, to be able to make medicines."
Mr Smith has pledged in inject more funds in to the NHS, calling for a 4% real-terms increase in spending in every year of the next parliament, part-funded by a "wealth tax" on the richest 1%.
Mr Corbyn says he would make the NHS fully publicly funded and bring services provided privately "back into public hands" and he would also "integrate the NHS and social care for older and disabled people, funding dignity across the board and ensure parity for mental health services".
His other pledges include curbing private finance contracts in NHS hospitals and reversing government plans to replace publicly-funded bursaries for nurse and midwife training with student loans.
Jeremy Corbyn has vowed to protect the welfare state and tackle inequality, neglect, insecurity, prejudice and discrimination.
In 2015, he was among almost 50 Labour rebels who defied party orders to abstain on the government's Welfare Bill. The legislation included plans to limit child tax credit to two children. Mr Smith abstained, before voting against the bill in its third reading.
Mr Smith has backed increasing welfare payments and, on other occasions, voted against welfare cuts. He has supported the principle of the government's much troubled Universal Credit - an attempt to streamline several in-work benefits. But he attacked cuts to its budget and this year called for a review of the plans. He says he would abolish the Department for Work and Pensions, and replace it with a Ministry for Labour and a Department for Social Security.
Democracy and trade union rights
Both men say they would repeal the government's Trade Union Act. Mr Corbyn has set out detailed plans to boost democracy, including the devolution of power to local councils, regions and nations, replacing the House of Lords with an elected second chamber and ending what he sees as a "revolving door" corporate grip on politics and the civil service.
He would also aim to increase democracy in the community through more participation in budgeting and control of local services and he would introduce a citizens' right to challenge the outsourcing and privatisation of local services through referendums.
Mr Smith has proposed a five-year ban on party donors, MPs, advisers and staff receiving honours. He says that would include Shami Chakrabarti, who was nominated for a peerage by Mr Corbyn after conducting an inquiry into anti-semitism in the party.
He said: "Shami Chakrabarti is a highly respected human rights lawyers who has been a tireless civil liberties campaigner for many years.
"The timing of her appointment to the House of Lords, however, was unfortunate in light of her role as an independent adviser to the Labour Party."