I'd argue that there's actually no difference in his behavior. Trump has been consistently divisive, untruthful and inflammatory since day one. What has happened is that his sustained behavior has radicalized a significant fraction of the population to the point that they are convinced that everyone else is lying to them and there's a massive conspiracy against their god-leader. I don't want to run afoul of Godwin's Law here, but if you ever wonder how people ended up following leaders like Stalin, Franco or Mussolini - it was a process of years. People who called this out as dangerous from day one were ridiculed as alarmists or partisans.