The explosive devices sent to George Soros, the Clintons, the Obama and CNN constitute a terror attack, says NYC Mayor Bill de Blasio:

But when an actual pressure-cooker bomb went off in Chelsea in 2016, the mayor cautioned against calling that a terror attack until more information was known:

From the New York Times:

Seeking to project a responsible and measured reaction, the mayor pointedly avoided calling the bombing in the Chelsea neighborhood of Manhattan on Saturday that injured 29 people — and the presence of a seemingly related but undetonated device a few blocks away — a possible act of terror, declining at several points on Sunday to do so. He emphasized that there would be no “easy answers” and that no suspect had yet been apprehended.

Absent a motivation, Mr. de Blasio suggested the word terrorism should not be used, shaking his head in disapproval at the notion that the basic facts of the bombing could be described that way.

“Here is what we know: It was intentional, it was a violent act, it was certainly a criminal act, it was a bombing — that’s what we know,” he said on Sunday, flanked by law enforcement officials at Police Headquarters in Lower Manhattan. “To understand there were any specific motivations, political motivations, any connection to an organization — that’s what we don’t know.”

The approach appeared to be aimed at calming nerves in a city on edge, and at avoiding a rush to conclusions, both in New York City and across the country.

Yes, mayor … it was a really Scooby Doo mystery that had no clues attached to the bomb or anything like that:

A note found on the pressure cooker bomb left on 27th Street in Manhattan Saturday referenced Anwar al-Awlaki, the American-born al-Qaida-linked cleric killed in a U.S. drone strike in 2011, and the Boston Marathon bombings, a law enforcement official familiar with the investigation tells NBC News.
The note, described by one official as “a hodge podge, a rambling, disconnected, choppy series of references to past events,” also mentioned the 2009 mass shooting at Fort Hood, where a U.S. Army major and psychiatrist killed 13 people and injured 30 others.

Ahmed Khan Rahimi, the “unrepentant, homegrown Islamic terrorist” was sentenced to life for the attack:

And it sounds like his prison stay is going really well: