photometer vs light meter

photometer and light meter both are nouns.

Word	Noun	Adjective	Verb	Adverb
photometer	Yes	No	No	No
light meter	Yes	No	No	No

As nouns, photometer and light meter are synonyms defined as:

photometer and light meter: photographic equipment that measures the intensity of light

Other synonyms of photometer include exposure meter.

photometer (noun)	light meter (noun)
photographic equipment that measures the intensity of light	photographic equipment that measures the intensity of light
measuring instrument for measuring the luminous intensity of a source by comparing it (visually or photoelectrically) with a standard source