flue vs pipework

flue and pipework both are nouns.

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

As nouns, pipework is a hypernym of flue; that is, pipework is a word with a broader meaning than flue:

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

Other hypernyms of flue include organ pipe, pipe.

flue (noun)	pipework (noun)
a conduit to carry off smoke	the flues and stops on a pipe organ
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