Jeff Bezos, the world’s wealthiest person, revealed in a sensational blog post on Thursday that he believed he was the victim of “extortion and blackmail” by the company behind The National Enquirer. He accused the company, American Media Inc., of threatening to release graphic photos of him.

[Read more on the Amazon founder’s accusation and the fallout.]

Legal definitions aside, there is a foolproof definition for blackmail and extortion, according to William N. Nettles, the United States attorney in South Carolina from 2010 to 2016.

“They are like fancy bullying,” Mr. Nettles said.

Extortion vs. blackmail

Extortion and blackmail are similar concepts with overlapping definitions. “They are very, very similar,” Mr. Nettles said. “You could say that blackmail is a specific subset of extortion.”