filament vs fibril

filament and fibril both are nouns.

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

As nouns, filament and fibril are synonyms defined as:

Other synonyms of filament include strand.

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