organ pipe vs pipe organ

organ pipe and pipe organ both are nouns.

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

organ pipe (noun)	pipe organ (noun)
the flues and stops on a pipe organ	wind instrument whose sound is produced by means of pipes arranged in sets supplied with air from a bellows and controlled from a large complex musical keyboard