rain gauge vs pluviometer

rain gauge and pluviometer both are nouns.

Word	Noun	Adjective	Verb	Adverb
rain gauge	Yes	No	No	No
pluviometer	Yes	No	No	No

As nouns, rain gauge and pluviometer are synonyms defined as:

rain gauge and pluviometer: gauge consisting of an instrument to measure the quantity of precipitation

Other synonyms of rain gauge include rain gage, udometer.

rain gauge (noun)	pluviometer (noun)
gauge consisting of an instrument to measure the quantity of precipitation	gauge consisting of an instrument to measure the quantity of precipitation