Trump is different. When he is caught lying, he will often try to discredit people telling the truth, be they judges, scientists, F.B.I. or C.I.A. officials, journalists or members of Congress. Trump is trying to make truth irrelevant. It is extremely damaging to democracy, and it’s not an accident. It’s core to his political strategy.

As for Obama: His falsehoods tended to be attempts to make his own policies look better or to overstate a problem he was trying to solve. In a few cases, they seemed to be careless exaggerations he avoided repeating.

Over all, Obama rarely told demonstrable untruths as president. And he appears to have become more careful over time. We counted six straight-up falsehoods in his first year in office. Across his entire second four-year term, we counted the same number, six, only one of which came in his final year in office.

In all, we found 18 different bald untruths from Obama during his presidency. Trump told his 18th separate untruth in his third full week in office, and his list keeps growing.

https://www.nytimes.com/interactive/2017/12/14/opinion/sunday/trump-lies-obama-who-is-worse.html?rref=collection%2Fsectioncollection%2Fopinion&action=click&contentCollection=opinion&region=stream&module=stream_unit&version=latest&contentPlacement=12&pgtype=sectionfront&_r=0