need to make clear which one. So I could say, "Bob who works at the bank just bought a new car." Sometimes when we use a restrictive clause like this we add "the" before the subject, as in, "The Bob who works at the bank just bought a new car."
On the other hand, if I wanted to tell you that Bob bought this car, and as a side note mention that he works at the bank, I would use a non-restrictive clause. "Bob, who works at the bank, just bought a new car." Usually we do this when the clause is specifically relevant. Like, "Bob, who works at the bank that was robbed last week, bought a new car the day after the robbery."
Whether a clause is restrictiveA feisty British Civil Servant searches for the people who murdered her friend at a Brexit protest, putting herself in the crosshairs of an incompetent undercover police unit intent on pinning the crime on a slippery American whistleblower.

A no-nonsense London girl gets stuck with a broken American PR man

Targeted by the government’s own fake news

They must uncover a billion dollar crime

Before the Police catch up

BELLA RAVEN (31) is a sassy, sarcastic, no-nonsense Londoner. Party girl by night and by day, a very effective civil servant. She’s settled, great at her job and bored out of her mind. Her father, an NHS campaigner, has died suddenly and she’s wondering what she’s doing with her life.

Much to her surprise, she goes on a Brexit protest about selling off the NHS.