murmuration vs muttering

murmuration and muttering both are nouns.

Word	Noun	Adjective	Verb	Adverb
murmuration	Yes	No	No	No
muttering	Yes	No	No	No

As nouns, murmuration and muttering are synonyms defined as:

murmuration and muttering: a low continuous indistinct sound; often accompanied by movement of the lips without the production of articulate speech

Other synonyms of murmuration include murmur, murmuring, mussitation, mutter.

murmuration (noun)	muttering (noun)
a low continuous indistinct sound; often accompanied by movement of the lips without the production of articulate speech	a complaint uttered in a low and indistinct tone
	a low continuous indistinct sound; often accompanied by movement of the lips without the production of articulate speech