The distinction is sharp and important. The tl;dr version is that if you know a statement is false when uttered, that's lying. When you
don't care regarding its truthfulness, that ************. There's a whole, interesting essay on the topic; the
Wiki article on ************ is a good place to start.
The key here is that Trump doesn't care about the truthfulness of his statements. Hell, he will contradict himself in the same paragraph and not give a damn, figuring his ****kicker fans won't care either.
Maybe you can shame a liar and hope that he/she will get the facts straight. You can't shame a bull****er because, again, they don't care if they're right or wrong. The problem with Trump is perfectly illustrated by his recent interview with
Time. They told him before he showed up that the interview was going to be about his lying. But he didn't care. In that very interview
about lying, he lied about his lying. He repeated some of the same lies he's been called on before.
That's not a liar, that's a bull****er. An unbelievably brazen one.