Agree with Dean, Brexit is way worse. Trump is just one guy. He can't *do* anything without SCOTUS, Senate, House, whatever signing off on it. He could maybe start a war... But I really don't think that likely.
Brexit is as Dean said irreversible and will change a huge amount here in regards to workers rights, import / export tariffs, and so forth. Ironically, immigration (especially of the illegal kind) is likely to remain unchanged since a lot of it happens from outside EU, but there you go... Everyone gets the history they deserve as my dad says.