But first impressions are often misleading.
Yes, Spence is as soft-spoken as Nadeau-Dubois was fiery and yes, their causes could not be more different. She is starving herself in the name of one of the poorest constituencies in the country.
By virtue of their education opportunities, the students who Nadeau-Dubois led in a crusade against higher tuition fees last year make up the most privileged contingent of Quebec youth.
But like Nadeau-Dubois, Spence has attained a stature emblematic of a larger struggle, and in this, they are flip sides of the same coin. It is one that has the demonstrated potential to alter the power equation between governments and the governed.
A year ago today the student crisis that was about to take Quebec and its Liberal government by storm was not on anyone's radar.
Most of the early 2012 political analysis focused on opposition leader Pauline Marois' uphill battle to hang on to her job.
If the proposition had been put to the Quebec punditocracy or its ruling political class that a trio of student leaders was about to accomplish what a decade of Parti QuÃ©bÃ©cois attacks on premier Jean Charest had failed to achieve and mobilize the street against his government, it would almost certainly have been shrugged off.
Fatigue with Charest's three-term government played a large part in the making of Quebec's printemps Ã©rable. But the movement also featured a more fundamental rejection of the system itself.
To this day, a disquieting number of its participants believe that the traditional democratic channels - including the ballot box - have failed them. That feeling has long been widespread among Canada's First Nations.
Over the past decade, it has spread to ever-expanding pockets of politically engaged Canadians.
It does not help that so many of them have consistently failed to find an effective opposition outlet for their aspirations.
Charest's government was the main target of the student strife that eventually festered into the pot-banging Quebec maple spring, but the province's season of social unrest was also part of a larger grassroots pattern from which stems the Occupy movement on the global scene and, on the national stage, the momentum-gathering Idle No More movement.
It may not move the 99 per cent of Canadians that the Occupy movement claims to speak for, but the Idle No More spirit has the capacity to resonate with the more than 60 per cent of voters that consistently opt for federal options other than the Conservative party.
On the societal role of government, the gap between the various non-Conservative constituencies in this country has always been smaller than the gap between those who support the current government and those who don't.
The ranks of those who sympathize with the activist goals of the Idle No More movement stretch from Joe Clark, a former Tory prime minister on whose foreign affairs watch Canada embraced free trade with the United States, to the likes of Peter Julian, a former executive of the nationalist Council of Canadians, who is now energy critic for the NDP.
Against significant odds, social peace has mostly prevailed since Harper came to power. But his government has hardly gone out of its way to expand its tent.
If anything, it has been more content than its predecessors to draw lines in the sand between its tent and the comparatively smaller ones of its squabbling rivals.
A risk in to that approach is the number of people who feel left out in the cold tends to keep growing.
On that basis, the Idle No More movement - if left unattended - could snowball into the biggest challenge Harper has encountered since he was first elected as prime minister seven years ago.
Chantal HÃ©bert is a national affairs writer. Her column appears Tuesday, Thursday and Saturday.
Â© 2013 Torstar Corporation