Baygon,

There are many people who would not 'avoid Trump at a party'; starting with the millions of Americans who voted for him. But what you do not make clear in your title, "Why is Trump Different" is - different from what? He is certainly different from Obama, Clinton and the Bush clan. And, that's why he is now U.S president. Voters wanted someone different from that lot. If something isn't working, as was bleeding obvious with all Trump's predecessors, you try something different. Trump is very different. Does it matter why?

ttbn - the reason I posed the question is simply that the hostility that Trump is generating is unprecedented - yet his policies are, by and large, the sort of policies that you would expect from a Republican President. Moreover Republicans should be happy because he delivered them both the House and the Senate. So under any other president the Democrats would have accepted the change and the Republicans would have been keen to get on with the job. Yet this is not happening. Anyone who reads reports from the USA will discover that there are Republicans and Democrats who do not want him at any price. The only thing that really makes Trump different is his personality. Anyone who is familiar with USA history will know that there have been other presidents with similar policies where he is a genuine outlier lies in the fact that he is the first president who has not been able to create even a semblance of unity.

".... reason I posed the question is simply that the hostility that Trump is generating is unprecedented "

Unprecedented?
No one has tried to murder him yet, can't say the same for some of his predecessors.

Nix on Nixon he was down to 25% in 1974 and had peaches thrown at him.

Oops, wrong thread. Go Trumpy!

Over the last 100 years we've become very familiar with the rhetoric and body language of dictators. We've seen films of real ones and of even more fictional ones (with rhetoric and body language exaggerated) in movies and on TV. We've also seem film of the mass response to dictators. Donald Trump exhibits many of these behavioural and verbal traits. Just two examples that I've found disturbing (apart from his style at rallies): Trump looming intimidatingly behind Clinton in one of the debates, and the narcissistic petulance over the issue of how many people voted or attended the inauguration.
Now I'm not suggesting that Donald Trump is or will be a dictator, the checks and balances of the American government system should prevent that. But we are acutely aware of the style, the rhetoric, the body language etc. and we know how seductive that is to some, not necessarily because they are bad people, but often because they are looking for a saviour. They hear the promises, but ignore the undercurrent, even though in other circumstances they would pick up on it in an instant (in other words I don't think they are stupid, just human).
We know what this pattern has often led to in the past, and it makes sense to be afraid, or at the very least wary, especially if you are in a category that has been on the receiving end of the rhetoric.
What I have trouble evaluating is whether this style just 'is' Donald Trump, or whether it is deliberately adopted; there's evidence either way. I'm not sure which of these possibilities is worse: that he doesn't consciously know how his behaviour is read, or he does know and is laying it on intentionally. A bigger risk than the US protestors is how other countries will read it and react, given that many of them have had much greater experience with home-grown dictators, their own or their next-door-neighbours. In some respects USA is quite naïve in this matter, only dealing with dictators at a distance, and never having had one of their own.