A voltage tester is an electrician’s tool used to detect or test the voltages in varying circuits. It differs from a voltage detector both in the way it works (in contact with the supply) and the results you get from it (giving levels of voltage, rather than identifying its presence).
A voltage tester would be chosen over a voltage detector in instances where the user wishes to know levels of voltage for checking things are working properly, whereas a voltage detector would be chosen to identify whether voltage is present without touching the supply, before beginning any electrical project.
A tester determines a reading or value for something; in this case, voltage levels. Voltage testers include two probes and a box. The probes need to come into contact with the electrical supply to function.
Voltage testers can also be referred to as power testers, electrical test meters, electrical test probes and voltage checkers. These are names also used to refer to other, similar tools. The voltage testers here will always be the type that consists of two, individual probes, connected by a cable with a voltage indicator on one side.