As nouns the difference between mutter and rutter
is that
mutter is a repressed or obscure utterance; an instance of muttering while
rutter is a thing that ruts.
As a verb mutter
is to utter words, especially complaints or angry expressions, indistinctly or with a low voice and lips partly closed; to say under one's breath.
As a proper noun Rutter is
{{surname|lang=en}.