flue pipe vs pipework

flue pipe and pipework both are nouns.

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

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

flue pipe: 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 pipe include organ pipe, pipe.

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