What is the advantage of using a single thermocouple over a thermopile?

Question

The use measuring temperature i.e. using the thermocouple as a digital themometer with the emf being amplified and calibrated to record a specific temperature.

Answer 1

A thermopile is not used for measuring temperature, it is used for generating electricity. If its output were measured as an indication of temperature, it would change slowly.
A thermocouple can be made very small and thus measure temperature very quickly and in a precise location. Thicker wire makes it tougher, but also make changes in temperature slower to measure.