pipe vs flue pipe

pipe and flue pipe both are nouns.

Word	Noun	Adjective	Verb	Adverb
pipe	Yes	No	Yes	No
flue pipe	Yes	No	No	No

As nouns, flue pipe is a hyponym of pipe; that is, flue pipe is a word with a more specific, narrower meaning than pipe:

pipe: the flues and stops on a pipe organ
flue pipe: organ pipe whose tone is produced by air passing across the sharp edge of a fissure or lip

Other hyponyms of pipe include flue, labial pipe, organ stop, reed pipe.

pipe (noun)	flue pipe (noun)
a long tube made of metal or plastic that is used to carry water or oil or gas etc.	organ pipe whose tone is produced by air passing across the sharp edge of a fissure or lip
a tube with a small bowl at one end; used for smoking tobacco
the flues and stops on a pipe organ
a tubular wind instrument
a hollow cylindrical shape