flow meter vs device

flow meter and device both are nouns.

Word	Noun	Adjective	Verb	Adverb
flow meter	Yes	No	No	No
device	Yes	No	No	No

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

flow meter: a device used to measure mass or volumetric flow rate of a liquid or gas.
device: an instrumentality invented for a particular purpose

Other hypernyms of flow meter include measuring device, measuring instrument, measuring system.

flow meter (noun)	device (noun)
a device used to measure mass or volumetric flow rate of a liquid or gas.	any clever maneuver
	an instrumentality invented for a particular purpose
	an emblematic design (especially in heraldry)
	any ornamental pattern or design (as in embroidery)
	something in an artistic work designed to achieve a particular effect