mouth organ vs mouth harp

mouth organ and mouth harp both are nouns.

Word	Noun	Adjective	Verb	Adverb
mouth organ	Yes	No	No	No
mouth harp	Yes	No	No	No

As nouns, mouth organ and mouth harp are synonyms defined as:

mouth organ and mouth harp: a small rectangular free-reed instrument having a row of free reeds set back in air holes and played by blowing into the desired hole

Other synonyms of mouth organ include harmonica, harp.

mouth organ (noun)	mouth harp (noun)
a small rectangular free-reed instrument having a row of free reeds set back in air holes and played by blowing into the desired hole	a small rectangular free-reed instrument having a row of free reeds set back in air holes and played by blowing into the desired hole