shepherd's pipe vs treble recorder

shepherd's pipe and treble recorder both are nouns.

Word	Noun	Adjective	Verb	Adverb
shepherd's pipe	Yes	No	No	No
treble recorder	Yes	No	No	No

As nouns, shepherd's pipe and treble recorder are synonyms defined as:

shepherd's pipe and treble recorder: a small fipple flute with four finger holes and two thumb holes

Other synonyms of shepherd's pipe include flageolet.

shepherd's pipe (noun)	treble recorder (noun)
a small fipple flute with four finger holes and two thumb holes	a small fipple flute with four finger holes and two thumb holes
a small bagpipe formerly popular in France