Wendy Rahn and Eric Oliver write,
Of course, authoritarians and populists can overlap and share dark tendencies toward nativism, racism and conspiracism. But they do have profoundly different perceptions of authority. Populists see themselves in opposition to elites of all kinds. Authoritarians see themselves as aligned with those in charge. This difference sets the candidates’ supporters apart.
Once again, I recommend the whole post.
I think of populism as a dangerously self-negating approach to politics. The problem is that the people attach themselves to a charismatic leader, and that leader is bound to have the sort of arrogance that populists supposedly resent.