flue vs flue pipe

flue and flue pipe both are nouns.

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

As nouns, flue and flue pipe are synonyms defined as:

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

Other synonyms of flue include labial pipe.

flue (noun)	flue pipe (noun)
a conduit to carry off smoke	organ pipe whose tone is produced by air passing across the sharp edge of a fissure or lip
organ pipe whose tone is produced by air passing across the sharp edge of a fissure or lip
flat bladelike projection on the arm of an anchor