Trump's populism means danger of fascism because 1) glorification of violence & enabling paramilitary groups to go after perceived enemies; 2)places racism & xenophobia at center of politics; 4)conflates leader, movement & state institutions; 5) lies/fascist propaganda technique 
6) questions electoral procedures & legitimacy of elections/electoral system; 7) presents an extreme cult of the leader/similar to fascist forms of political religion; 8)presents political theology where the leader is equated with formal religion
9) separation between secular & sacred is shaken; 10) corruption & dissolution of distinction between leader's interest & state interest
10) myth replaces empirical reality & reality is changed in order to resemble the fantasies of the leader
11) attacks/demonizes the independent press precisely because journalists provides citizens with facts that put in question the caudillo's fantasies/propaganda & lies
12) modes of repression (Portland) which are typical of fascist inspired dictatorships
13) total conflation of people, leader & nation
14) demonization of enemies (all those that disagree with leader) as being against the nations
15) related point: the people thought as an ethnic/religious community rather than the sum of all citizens. This means anti-democratic reduction of the entire people to the people who follow the leader
there are many more elements that connect post-fascist populists like Trump, or Bolsonaro in Brazil, but let me conclude with why he is not fascist yet: he has not destroyed the free press or electoral system and in short he is a weak wannabe dictator but not a real one.
There is a very productive debate about this with @ruthbenghiat @DavidAvromBell @ppiccato @jasonintrator @samuelmoyn @Notorious_RSG @mabelberezin @Andrea_Mammone & other colleagues
For key bibliography I would also recommend he recent book by Geoff Eley, on nazism & fascism, especially the last part & also the works of Zeev Sternhell, Hannah Arendt & T. Adorno
