The nouns robber and thief refer to the person, the criminal: imaae source
The robbers ran away from the police.
The thief took my laptop and cell phone.
"Give me all your money!" the robber said.
The thieves were tall, white men who looked about 22 years old.
The robbery (n.) is the event:
Police are investigating the robbery of the Main Street Bank.
The robbery occurred at 4:30 PM.
Three employees were injured during the robbery.
The word theft (n.) describes the event or the crime (in the justice system)
He was sentenced to eight years in prison for the theft of a motorcycle.
We immediately called the police to report the theft.
Ken was accused of identity theft.
To rob (v.) is the action. It is often used in the past as robbed:
Donald robbed five stores before being caught by the police.
My favorite pizza shop was robbed last month. Luckily, no one was hurt.
I was robbed at gunpoint while walking home from work.
The verb steal and the adjective/past participle stolen refer to the action of taking something specific. These words are always used together with an object - the object that was taken.
The thief stole a gold necklace from the woman's bedroom.
Wendy's wallet was stolen on the subway.
Jim was caught stealing money from his own company.
Rachel tried to steal Carla's boyfriend.
To describe a thief entering a building, we can also use the phrasal verb break into: