Volt is the S.I unit of potential difference

Volt is comercial unit of potential differences 1volt = 1n of energy recquired to move 1 q of charge
The volt (symbolized V) is the Standard International (SI) unit of electric potential or electromotive force. A potential of one volt appears across a resistance of one ohm when a current of one ampere flows through that resistance.The volt (symbol: V) is the derived unit for electric potential, electric potential difference (voltage), and electromotive force. It is named after the Italian physicist Alessandro Volta.

Difference between potential energy is called volt or volt is measure by voltmeter
When 1j of work done by one coulomb of charge then electric potential is called one volt

Volt is the s.I unit of potential difference (P.D).