What is the difference between a thermocouple wire and a compensation wire?

A thermocouple wire is a wire used to make a thermocouple sensing point. The compensation wire is only used to extend the thermocouple signal to the instrument reading this signal. The compensation wire usually has a lower ambient temperature limit, that is, it can transmit signals from the probe at higher temperatures, but it is not itself exposed to higher temperatures. The thermocouple wire can be used as a compensation wire, but the compensation wire cannot be used to make the induction point (or probe part) of the thermocouple. Product numbers for compensation wires usually begin with the prefix "EX".