murmur vowel vs schwa

murmur vowel and schwa both are nouns.

Word	Noun	Adjective	Verb	Adverb
murmur vowel	Yes	No	No	No
schwa	Yes	No	No	No

As nouns, schwa is a hypernym of murmur vowel; that is, schwa is a word with a broader meaning than murmur vowel:

murmur vowel: a schwa that is incidental to the pronunciation of a consonant
schwa: a neutral middle vowel; occurs in unstressed syllables

Other hypernyms of murmur vowel include shwa.

murmur vowel (noun)	schwa (noun)
a schwa that is incidental to the pronunciation of a consonant	a neutral middle vowel; occurs in unstressed syllables