fibril vs filament

fibril and filament both are nouns.

Word	Noun	Adjective	Verb	Adverb
fibril	Yes	No	No	No
filament	Yes	No	No	No

As nouns, fibril and filament are synonyms defined as:

Other synonyms of fibril include strand.

fibril (noun)	filament (noun)
a very slender natural or synthetic fiber	a thin wire (usually tungsten) that is heated white hot by the passage of an electric current
	a threadlike structure (as a chainlike series of cells)
	the stalk of a stamen
	a very slender natural or synthetic fiber