Like the others said, it's a noun vs verb. Here's some more info about how I would understand it:
"To commit fraud" --> "совершить мошенничество" "Мошенник совершил Мошенничество." "Для совершения мошенничества."
"To defraud" or: cheat, deceive, trick, generally--> "обьманыват"
In English, generally, 'fraud' is a legalistic term although it can be used generally to describe deception, cheating, lying, false misrepresentation, scamming, etc.
Also, a person can be a fraud (i.e. a 'fake' or someone who misrepresents themself). This can be used for criminals/scammers, but is more often used to describe a person who is deceiving themselves or others due to some kind of inferiority complex or personality problems.