murmur vowel vs shwa

murmur vowel and shwa both are nouns.

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

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

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

Other hypernyms of murmur vowel include schwa.

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