The Populist Spectrum
Populism describes the relationship between a political movement and the political establishment. A movement is populist if it derives power from the masses and opposes the status quo entirely, rather than just opposing a specific force. This will either involve electing a political outsider, empowering a rogue elitist, or direct action. It will usually allege some sort of conspiracy within the establishment. Popularity within the movement is tied directly to the unpopularity of the establishment.
The populist spectrum describes political movements on a scale from populist to elitist.
Revolutionary
Political revolution is the extreme of populism. It rejects the political process entirely and uses direct action instead.
The Velvet Revolution was a very popular revolution in Czechoslovakia, mainly consisting of protests and strikes. The fact that it was largely nonviolent actually makes it less populist, because this constitutes some degree of compliance with the laws of the regime.
The Russian Revolution was similar, although perhaps not as popular, seeing as it devolved into civil war. It was also much more violent. You can’t really get more populist than murdering the royal family.
Populist
Populism, after which the populist spectrum is named, is somewhere in the middle of the spectrum. Populism is not revolutionary, and works within the system to elect an outsider. These movements will criticise the status quo, accusing it of dysfunction or outright corruption. They will often scapegoat a specific group of people, such as minorities, extremists or capitalists. They will also make some attempt to dismantle institutions, depending on how committed they are.
Adolf Hitler was a very successful populist. He initially pursued power through revolutionary means but eventually found success within the electoral system. Even during his dictatorship, he held up a veneer of legality and democracy. He scapegoated several groups, especially Jews, but really anyone who was not an ideal Nazi loyalist.
Popularist
Popularism is a strategy where establishment politicians focus on bipartisan legislation and popular policies. This is essentially just a representative democracy working as intended.
Bill Clinton was a successful popularist. He mostly pursued popular, centrist and sometimes even conservative policies using a Nixon goes to China style strategy called triangulation. This contributed to his reelection and average approval of 55%, making him the 5th most popular president.
Elitist
Elitism is rule by experts, professionals, aristocrats, monarchs, dictators, one-party states or philosopher kings. While these governments are often authoritarian for historical reasons, that is not what defines this end of the spectrum. What makes a government elitist is if decisions are made by leaders and not the public.
A good example of modern elitism is the chair of the Federal Reserve. The chair is nominated by the president and confirmed by the senate, so they’re elected by other elitists and only have an indirect democratic mandate. Furthermore, the chair is historically selected from elite institutions, and the position requires technical expertise, so there is little room for demagoguery.