PARIS — Stéphane Vardon has worked as a conductor on France’s high-speed and suburban rail network for 20 years. It is hard work, he says, and he’d like to retire before he turns 58, a privilege he now fears President Emmanuel Macron is going to strip away.

So this week, when nearly one million French citizens demonstrated nationwide to protect pension benefits that are the envy of much of the world, Mr. Vardon, 46, was among them, marching through the streets of Paris.

“People will have to work longer and have less money for their retirement,” said Mr. Vardon, citing a common fear of Mr. Macron’s plans. “Macron isn’t close to the people. We know he won’t do anything for the workers.’’

While France’s official retirement age may be 62, the actual age varies widely across the country’s labyrinthine system. Train drivers can retire at 52, public electric and gas workers at 57, and members of the national ballet, who start dancing at a very young age, as early as age 42. That is to name just a few of the stark differences.