Mail fraud, unsurprisingly, requires use of the U.S. postal service to commit fraud. Wire fraud, on the other hand, involves wire-based communications including telephone, fax, television, text message, and internet.
Mail fraud and wire fraud are each specifically defined as crimes under federal statute. The definition of mail fraud is a bit simpler – in a nutshell, it is devising or carrying out a scheme to commit fraudulent acts using the mail. Wire fraud sounds more complicated – it requires an intentional scheme to defraud another out of money, with a reasonable expectation that interstate wire communications would be used and in the end are in fact used. However, federal courts have made clear that the wire fraud statute is a parallel to the mail fraud statute and the only difference is the type of communication used.