diopter vs unit of measurement

diopter and unit of measurement both are nouns.

Word	Noun	Adjective	Verb	Adverb
diopter	Yes	No	No	No
unit of measurement	Yes	No	No	No

As nouns, unit of measurement is a hypernym of diopter; that is, unit of measurement is a word with a broader meaning than diopter:

diopter: a unit of measurement of the refractive power of a lens which is equal to the reciprocal of the focal length measured in meters; used by oculists
unit of measurement: any division of quantity accepted as a standard of measurement or exchange

Other hypernyms of diopter include unit.

diopter (noun)	unit of measurement (noun)
a unit of measurement of the refractive power of a lens which is equal to the reciprocal of the focal length measured in meters; used by oculists	any division of quantity accepted as a standard of measurement or exchange