LONDON — The differences in approach could not be more distinct — or telling.


Two of the most economically distraught euro zone countries, Greece and Spain, mapped out further budget-cutting plans last week.


In the case of Greece, under last-chance pressure from its international creditors, the governing coalition tentatively agreed on an austerity package that includes some of the most severe cuts in public pensions ever imposed in a developed country. Pension payouts to retirees would be trimmed by as much as 10 percent.


And then there was Spain, where last Thursday the government of Prime Minister Mariano Rajoy introduced one of the most draconian budgets in the country’s history. It was meant to reassure international investors and demonstrate the fiscal discipline that the euro zone was demanding of Madrid. The markets need reassuring: Spain has a stubbornly high budget deficit, its banks require tens of billions of euros in rescue loans and the government may soon have little choice but to request European aid.


Nevertheless, Mr. Rajoy declined to cut pensions — or even to freeze them. Instead, his budget would actually increase pension payouts 1 percent next year. The money includes not only pensions for former public employees, but also the social security payments that go to all retired Spaniards.


Politically, it is understandable that Mr. Rajoy would want to put a protective bubble around the country’s 10 million retirees at a time when people are marching in the streets and the economically crucial region of Catalonia is threatening to secede.


But pension expenditures represent the single biggest line item in the Spanish government’s budget, at nearly 40 percent of public spending and 9 percent of Spanish gross domestic product.


That 9 percent still trails France (15 percent) and Italy (13 percent). But given Spain’s rapidly aging population — 30 percent of Spaniards are expected to be older than 65 by 2050 — the portion of government spending on pensions seems certain to rise in the future.


The fact that Spanish public pensions are not only off limits to the budget knife but also are being enhanced, is a reminder of one reason that European debt and deficit problems have proved so difficult to resolve.


Only Greece, under duress and at a point where the move may be coming too late to salvage the government’s finances, seems prepared to risk the consequences of severe pension cutting.


By contrast France, under its new president, François Hollande, has lowered its retirement age to 60 from 62, for certain categories of workers. To be sure, the French budget outlook is not as dire as that of Spain.


But over the longer term the deficit-reduction plan that Mr. Hollande’s government unveiled with much fanfare Friday could have a limited effect because it left pensions largely untouched.


Meanwhile Portugal, under pressure from a fresh wave of street protests, is likely to rescind a bold plan that would have forced workers to increase their personal contributions to pension plans. And in Britain, the coalition government of Prime Minister David Cameron continues to resist any pension changes that would come down hard on elderly conservative voters.


“These policies are unsustainable,” said Jagadeesh Gokhale, an expert on pensions and social spending at the Cato Institute, a politically conservative research house in Washington. “The implicit liabilities of the pension programs will soon turn into explicit debts. But the political dynamic in Europe is opposed to policies that make economic sense.”


To be sure, in Spain, pensions have become a critical lifeline. With the unemployment rate at 25 percent, and even higher among young people, many Spaniards have become reliant on pension-drawing parents and grandparents to support them. Economists estimate that as many as 1.7 million of Spain’s 16 million households, have no salary earners.


Arguably, then, Spain’s pension benefits are more important than unemployment insurance, a benefit for which eligibility eventually expires.