muscae volitantes vs musca volitans

muscae volitantes and musca volitans both are nouns.

Word	Noun	Adjective	Verb	Adverb
muscae volitantes	Yes	No	No	No
musca volitans	Yes	No	No	No

As nouns, muscae volitantes and musca volitans are synonyms defined as:

muscae volitantes and musca volitans: spots before the eyes caused by opaque cell fragments in the vitreous humor and lens

Other synonyms of muscae volitantes include floater, spots.

muscae volitantes (noun)	musca volitans (noun)
spots before the eyes caused by opaque cell fragments in the vitreous humor and lens	spots before the eyes caused by opaque cell fragments in the vitreous humor and lens