The object of 'steal' is what is taken. You steal money, you steal jewellery. The object of 'rob' is the person from whom the object was stolen or the place from where it was taken. You rob a bank, you rob a rich person. A bank was robbed, and £1m was stolen.

Su Ki's answer is a good description of how the word is used in common speech. However, technically, robbing and stealing are two different things and it's only common ignorance of the difference that leads to the two meanings being merged in modern speech. The Free Dictionary defines robbery as : The taking of money or goods in the possession of another, from his or her person or immediate presence, by force or intimidation. http://legal-dictionary.thefreedictionary.com/robbery So, technically, it would be wrong to say that "the bank robbers entered the bank at night and robbed it of 1 million dollars" because to "rob the bank", they would have had to take the money from the bank employees. But, in common speech, people don't usually make this distinction and they will say that the bank robbers "robbed the bank" whether the crime happened during the day or at night. There is a phrase in English "this is highway robbery". To understand the phrase, you have to imagine a nobleman and his retinue riding along the road (the "highway") and being held up by Robin Hood and his Merry Men (or another group of highway robbers) and having their gold stolen. Also worth noting is the fact that "to steal" has multiple definitons: 1) take something unlawfully: to take something that belongs to somebody else, illegally or without the owner's permission 2) take something furtively: to take or get something secretly, surreptitiously, or through trickery (definition taken from the Bing dictionary) When we say that Robin Hood and his Merry Men "stole" gold during a highway robbery, we are using definition #1. However, if they "stole" into the castle and took the gold without anyone knowing, that is definition #2.

Steal is when someone takes secretly something that belongs to someone else. For example: When someone takes your car from a a parking or if a burglar breaks into your house and steal your TV, but you didn't realized. Rob is when someone takes money or property from a person or place, often using violence. You use "rob" when someone with a gun walks in a bank and demands money. Sometimes when someone attacks and robs violently, in an informal way "mug" is used. By the way, there are other verbs to describe these actions that in portuguese could be equal, but in english are defined in different words, for example: Shoplift is when you take goods from a shop without paying for them (for example someone takes a shirt from the local department store without paying);