photometry vs mensuration

photometry and mensuration both are nouns.

Word	Noun	Adjective	Verb	Adverb
photometry	Yes	No	No	No
mensuration	Yes	No	No	No

As nouns, mensuration is a hypernym of photometry; that is, mensuration is a word with a broader meaning than photometry:

photometry: measurement of the properties of light (especially luminous intensity)
mensuration: the act or process of assigning numbers to phenomena according to a rule

Other hypernyms of photometry include measure, measurement, measuring.

photometry (noun)	mensuration (noun)
measurement of the properties of light (especially luminous intensity)	the act or process of assigning numbers to phenomena according to a rule