Bernie Sanders is an old-school progressive who believes most of the country’s problems can be traced to class and economics. Meanwhile, contemporary progressivism is more committed to multiculturalism and the idea that America’s biggest injustices remain inextricably tied to race.
On a lot of substantive policy issues, this is a distinction without a difference. Most liberals recognize there is a strong relationship between economics and structural racism. Sanders favors most of the same policies his multicultural critics do and is even, on balance, pretty supportive of high levels of immigration.
But there are important differences rhetorically and in terms of how you conceptualize the government’s obligations. You don’t have to believe Sanders has anything in common with Joseph Stalin’s politics to recognize that he is also talking about “socialism in one country.”
Sanders favors a robust welfare state and wants the government to mandate generous wages and working conditions. But he wants those things for Americans, not necessarily all the people living all across the globe whose standard of living could theoretically be improved by residing in America instead.