Only once in a generation does a US presidential election coincide with a scheduled Chinese leadership change. This year the juxtaposition offered a special piquancy because of the perception that China is well advanced on its inexorable way up in the world, and the United States is condemned only to go down. When next the two changes of administration coincide, if they do, in 20 years' time, China – even according to the most conservative forecasts – will have knocked the US off its global economic perch and be well on its way to registering a gross domestic product that is twice as big.

The coming change of global economic guard, however, was hardly reflected in the media coverage of the two events, as seen from this country last week. Pages of newsprint were devoted to the US election, with the BBC transporting itself lock, stock and barrel to the US. The voting across the Atlantic was treated with almost as much small-print attention as a domestic poll – which, for those Britons who subscribe to the special relationship or see the malign hand of US imperialism in every corner of the world, you might argue that it was. You had to know your Pennsylvania from your Wisconsin.

There were practical grounds for the disparity, too. The US election was the culmination of what was described as the longest, most expensive and most negative campaign in the country's history. Voters conveniently speak English, and are mostly happy to voice their opinions in front of television cameras. More to the point, the final outcome was not known until we had heard from Ohio in the small hours of the morning.

The Chinese Communist Party Congress might have mystery – its timing was announced only a few weeks in advance and the precise way in which the party's top officials are chosen is opaque, as are even the parameters of their subsequent responsibilities – but it also has tediously long speeches, minute stage-management and an outcome, at least for the top job, that was arranged and made public long in advance. The breaking news would be if Vice-President Xi Jinping did not take over as President and party chairman from Hu Jintao next week. Yet if there had been the slightest possibility of an upset, the congress itself would not have been convened. The whole point of this five-yearly gathering in Beijing's Great Hall of the People is to demonstrate harmony and order.

That lack of excitement, the hyper-formality, and the condescension that Westerners tend to reserve for foreign leadership changes that do not entail an election, at least not an election as we know it, combine to explain why the confirmation of President Xi will not compete with the re-election of President Barack Obama for European airtime.

But there are two reasons why the contrast between the relative calm in China and the raw excitement of a US presidential race is deceptive, at least this time around. The first is that the changes to be finalised in China over the coming days envisage a far longer time scale than anything US politics has to offer. Across the Atlantic, the White House will once again be in play well before Mr Obama's second four years are up. New faces will emerge, with new profiles, to match the shifting dynamics of the country. A US president, especially if he can bend Congress to his will, wields more power – political, economic and military – than any other national leader in the world. But it is power that is finite, and no president can dictate a lasting legacy.

In China, President-designate Xi is the product of a selection process that began at least three party congresses ago – which means that the leaders of 20 years, even a quarter of a century hence, are being lined up this week, leaders who may or may not be equal to the job of managing a very different China. The extent to which a new leader must nod to continuity rather than change was evident from the historical tributes in Hu Jintao's opening speech. Gradualism is seen as a virtue in Chinese politics, after the spasms of the 20th century.

The other reason for resisting the seduction of US politics and switching at least some of the attention to China is the scale of the uncertainties that lie ahead. However radical or reformist a new US president promises to be, however different, in Obama's case, his face, the change makes relatively few ripples in American society because of the stability and entrenched nature of all the other institutions. Even the tied election of 12 years ago prompted only the slightest wobble in the body politic. The Constitution, which prescribed what should happen next, held firm. And although some voters never quite accepted George W Bush's presidency as legitimate, his victory was endorsed by the Supreme Court and he won a new mandate four years later. From the US Congress through the state legislatures, down – as they say – to dog-catcher, the country's representative institutions remained solid, as they did – thanks largely to government intervention – through the 2008 banking crisis.

Whether or not you view electoral democracy as the system that defines a civilised country – the worst system, as Churchill is supposed to have said, except for all the others – China is at a quite different stage of its development, and not only politically. It is as unrealistic to expect China to maintain its present high growth as it is to expect an advanced industrialised country to enjoy a growth rate in double figures, unless – as with former communist countries – its development had been artificially arrested.

For 30 years, China has enjoyed an economic miracle. But, like all miracles, it is a one-off, reflecting the low level of development that went before, rapid – if patchy – industrialisation, a sharp increase in the population of working age, and an almost insatiable appetite in the developed world – until recently – for goods made with China's cheap labour. All those indicators are changing – in ways that are good, because they mean that many Chinese are living vastly better than their parents and grandparents, but in ways that also carry enormous risks.

When China last erupted, in the Tiananmen Square protests of 1989, the pressure was largely political and led by students. Those classical flag-bearers of a revolution, the workers and peasants, failed to join in substantial numbers. A united and engaged leadership might have nipped what was largely a student movement in the bud, but inherited divisions fostered indecision and, in the end, brought the panicked order that sent in the tanks.

The experience of 1989, reinforced by the collapse of communism across Europe, is imprinted on the Chinese leaders of today. But it is not at all clear that they have any remedies for the local discontent that is welling up in many parts of the country. Low pay, harsh working conditions, rural backwardness and land-grabs by the powerful are all heating a cauldron that threatens to boil over.

It is easy for outsiders to insist, with more than a glance at the smooth re-election of Obama, that the extension of democracy beyond modest grassroots experiments is the only solution for China. But that runs up against the party's determination to retain its monopoly, a society suspicious of campaigning as a recipe for instability, and – probably – a shortage of time. Expectations are outrunning reality, and there are no social or political institutions ready to pick up the slack.

The apprehensions of the ruling class are such that they no longer need decoding. In his valedictory speech, Hu Jintao paid lip-service to reform of the political structure as "an important part of overall reform", and spoke of the need for a new economic growth model – neither exactly small tasks. Calling for vigilance against corruption, though, his language was nigh on apocalyptic: "If we fail to handle this issue well, it could … even cause the collapse of the party and the fall of the state".

A political crackdown, limited use of military force, even conjuring up the spectre of a foreign enemy (Japan) are ways China's Communist rulers might be tempted to try to buy time – but each could prove more destabilising than an attempt to control political change. Over the next 10 years Xi Jinping is the man who will have, in the last resort, to clinch the alliances and agree the compromises that could spell the difference between a peaceful transition for a fifth of the global population and chaos. Does this make him any less significant to the world's future than Barack Obama?

It is now almost a quarter of a century since Mikhail Gorbachev, then leader of the ruling Soviet Communist Party, set out for China to meet Deng Xiaoping and seal the end of the Sino-Soviet schism. It was not the grand occasion either side had hoped for. Gorbachev's power was already ebbing; Deng was so frail he could barely manage the totemic handshake. The timetable for the whole visit was perpetually disrupted by the unruly encampment of protesters on Tiananmen Square.

Nor was the ideological split really over; it had merely changed shape. Chinese ideologues blamed contamination from Gorbachev's perestroika (restructuring) for the demonstrations shaking their own regime, while Russians could not decide whether to be critical or envious of China's rush to consumerism. They consoled themselves with the wisdom of one of the ageing Russian sinologists invited to be part of Gorbachev's entourage. The astounding plenty around them, he said, was all very well, but "China has yet to experience its version of our 1905 revolution, let alone its 1917".