The difference between voltage and potential difference

In this paper some basic terms such as voltage and potential difference are presented. In many cases they are regarded as identical which leads to confusion with understanding of the fundamental concept of electromagnetic field. Related to this topic, some authors in their books and papers on electromagnetic theory have discussed what the voltmeter actually measures, which is resolved here in a simple way. In this paper it is shown that there is a difference between the terms voltage and potential difference depending on what is the observation point static fields or time-varying fields. Also in the transmission line model, the voltage between two points depends on the path of integration and, therefore, is ambiguous. What is commonly referred to as voltage, is transversal voltage that is a special case of voltage equal to the potential difference that is unique. Similarly, in electrical circuit analysis, branch voltages are unique and equal to difference of nodal voltages (nodal potentials).