Common law fraud refers to a deliberate misrepresentation of a material fact made with the intent to deceive and induce another party to take action or relinquish a right. Money paid by mistake, on the other hand, refers to a payment made unintentionally or due to an error. For example, if a provider submits a claim for a service that was not actually provided, that would be an example of common law fraud. If a provider accidentally submits a claim for the wrong amount, that would be an example of money paid by mistake.