Voltage - is the term for electrical energy (pressure if you will) measured from a power source. In the US, the wall outlet is rated between 115 -120 volts AC @ 60 Hertz. Volt - is also a unit of measure used in technical environment. i.e. 12 vDC outlet in your car, or a 5 volt charger for your cell phone. For your question, "voltage", as already given to you, is correct.