sextant vs measuring device

sextant and measuring device both are nouns.

Word	Noun	Adjective	Verb	Adverb
sextant	Yes	No	No	No
measuring device	Yes	No	No	No

As nouns, measuring device is a hypernym of sextant; that is, measuring device is a word with a broader meaning than sextant:

sextant: a measuring instrument for measuring the angular distance between celestial objects; resembles an octant
measuring device: instrument that shows the extent or amount or quantity or degree of something

Other hypernyms of sextant include measuring instrument, measuring system.

sextant (noun)	measuring device (noun)
a measuring instrument for measuring the angular distance between celestial objects; resembles an octant	instrument that shows the extent or amount or quantity or degree of something
a unit of angular distance equal to 60 degrees