In the good old, bad old days when Labour had a strange compulsion for committing suicide in public, the party's uncivil wars were bloody, but at least they were easy to follow. You knew where you were when the Bevanites were slugging it out with the Gaitskellites in the 1950s. As you did when the Bennites were battling with the Healeyites in the 1980s. Those fratricidal frenzies helped to put Labour out of power for long stretches, but the one redeeming feature of the divides of the past is that the battle lines were vividly drawn.

Ed Miliband's Labour is not noisily split along left-right lines. Though his senior team seethes with plenty of personal rivalries, the lid has been kept on them for most of the time. That is one of the lesser sung achievements of his leadership of a historically fissiparous party. It doesn't mean that Labour is not divided. The difference is that the fault lines these days are more complex and various. I offer you my attempt to delineate the five Labour divisions that matter at the moment.

Thirty Five Percenters v Majoritarians

This is essentially an argument about what Labour should be realistically attempting to achieve at the next election. Thirty Five Percenters note that it is mathematically feasible for Labour to win power with that share of the vote. It may even be possible for Ed Miliband to stagger over the threshold of Number 10 with something less. Hang on to the support they have, factor in the bias in the electoral system against the Conservatives and the damage that will be done to the Tories by Ukip, and Labour could be home and dry.

It sounds miserably unambitious so no Labour figure will admit, publicly or privately, to being a Thirty Five Percenter. But there are quite a lot of furtive ones about.

Majoritarians reckon Labour ought to be aiming higher, partly because they believe it is good in itself to try to maximise vote share, partly because they fear a Miliband government would not have much authority if it came to power with thin support. They are not so crazy as to believe that Labour could win an actual majority of votes; no party has managed that in decades. But they do think they should be aiming high. The Majoritarians struggle to explain from where precisely additional support is going to come. Defectors from the Lib Dems and other home-comers are already in the Labour column. The only way to boost vote share significantly would be to woo voters directly from the Tories. One of the stories of this parliament is that there has been very little movement between the two biggest parties. We will have a clearer idea of who is prevailing in this argument when Labour's target seat strategy is properly revealed. This split meshes with another…

Transformers v Realists

The Transformers contend that Labour needs to make a big and bold offer to the country at the next election even if that entails taking some risks. Quite a lot, though not all, of them are also secret Thirty Five Percenters. They'd rather go to the country with a radical manifesto than water it down in the pursuit of centrist voters.

Everyone would like to think of themselves and be thought of as a Transformer, including the representatives of the 19 thinktanks who wrote to the Guardian arguing that a "play it safe" election strategy would be a mistake because the challenges facing Britain were so "unprecedented" that Labour needed to secure a mandate for "transformative change".

The missive, which was interpreted as a challenge to the party's direction, caused consternation and irritation in the office of the Labour leader. Says one of his advisers: "Ed could have signed that letter himself."

I guess the real target of that letter were those in the party's senior ranks who could be described as Realists or, more pejoratively, as Shrinkers. They reckon the electorate is too cynical and mistrustful to buy grand visions of a New Jerusalem, especially if they sound as if they'd be expensive. On this reasoning, the way to power is to "shrink the offer" and present a modest prospectus to the country.

Douglas Alexander, the campaign chief, and Jon Cruddas, the co-ordinator of the policy process, are sometimes caricatured as the representatives of this divide. That is unfair to both men. It is more nuanced than that, but this argument is real and live. One member of the shadow cabinet says: "There is this unresolved question whether to keep our mouths shut and work on the assumption that governments lose elections or whether we come up with big ideas commensurate to the challenges of our time."

Who is right? Neither. Labour requires an ambitious vision for the country, but it won't get a hearing if the party is not also trusted. Labour does not need to present a programme that is just transformative or simply credible. It needs to find a way of sounding both.

Devolvers v Centralisers

This is a profound and important fault-line with big implications for how Labour might govern that has received very little attention. It is likely to become more visible in the weeks ahead as the party starts to publish a lot of additional policy. Mr Cruddas and like-minded colleagues think a Labour government should execute a dramatic transfer of power and money away from central government. Local councils would gain much more control over everything from economic development to delivery of public services. One proponent of this view, consciously borrowing from the debate about the future of Scotland, calls it "devo-max".

This is not a traditional left-right split. Exponents of devolution include the former Blairite cabinet ministers Andrew Adonis and Liam Byrne. Resistance is coming from more conventionally-minded types on both left and right. Some fear that it would lead to wide disparity of provision: "the postcode problem". Others worry they'd end up handing over too much power to councils run by Tories. It is also a challenge to Labour views that social change is most effectively achieved by central state action.

Ed Balls is regarded as a key figure in this debate. There is a traditional Treasury objection to loosening the reins of control, which is almost invariably shared by chancellors and would-be chancellors. During his many years at the right hand of Gordon Brown, Mr Balls was not exactly renowned as a man who liked to let go. I'm also told that "there is a lot of caution in the leader's office" about embracing this agenda. Well-placed observers say it is not yet clear which way Ed Miliband will jump.

Ed v Ed

Hints of the tensions between the putative prime minister and the candidate for chancellor occasionally come into public view. Mr Balls never looks like a man who shares the leader's enthusiasm for a "new economic paradigm". He avoids making speeches about it. Among allies of Mr Miliband, there is evident frustration with what is seen as the shadow chancellor's failure to do more to establish Labour's credentials as fiscally responsible.

The complaint is not so much about the content as about how it is being communicated. It may not have been intended as an unfriendly act, but Mr Balls did not do Mr Miliband any favours by suggesting that the leader messed up his response to the budget because he'd been too obsessed with following speculation on Twitter.

On the whole, though, they have kept their arguments under wraps. There have not been the vicious briefing wars that characterised Tony Blair's bitter struggles with Gordon Brown. When there is a bad dispute between the two Eds, it is commonly resolved at a one-to-one meeting. The advantage is that this makes it much less likely that their most bitter arguments will leak into public view; the disadvantage is that no one else can be sure what secret trades and deals they may have done.

Gloomsters v Zennists

Gloomsters have long considered Labour's opinion poll lead to be soft and at risk of melting away like frost touched by spring sun once a sustained economic recovery took hold. Their numbers include Labour MPs who fret that the living standards agenda so beloved of their leader is going to be stale by the time of the election. They have gained some recruits among Labour MPs in the wake of the budget. The number of Labour MPs who have publicly voiced any anxiety is precisely two, but plenty more are agitated about the poll bounce for the Tories. The Gloomsters may attract some more adherents as a result of the Opinium poll that we publish today that suggests that Labour's advantage over the Tories has shrunk to just one point.

The Zennists argue that there is nothing to panic about. The post-budget poll bounce for the Tories is merely the result of the Conservatives winning back some silvery rightwing voters from Ukip. Who is correct? Both have a point. The main traffic at the moment does appear to be between the Tories and Ukip, but the Labour poll rating is unimpressive. Were the Tories to move into the lead, more of the Gloomsters are likely to go public with their fears.