A progressive isn’t simply a liberal. Liberal as a political identity is so 20th-century, so pragmatic, so Roosevelt-Clintonian. Liberals aren’t allowed to criticize each other apart from Democratic primaries, which all liberals vote in because liberals aren’t allowed to belong to other parties. But progressives pop up in all kinds of parties.
Liberalism has become a way of doing politics. It’s ceased being a real ethos or guiding light. Progressivism, it seems to me, has much more to do with articulating equal rights and equal protection for all.