filament vs myofibril

filament and myofibril both are nouns.

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

As nouns, myofibril is a hyponym of filament; that is, myofibril is a word with a more specific, narrower meaning than filament:

filament: a very slender natural or synthetic fiber
myofibril: one of many contractile filaments that make up a striated muscle fiber

Other hyponyms of filament include barb, cobweb, gossamer, chromatid, myofibrilla, sarcostyle, rhizoid, hypha, paraphysis.

filament (noun)	myofibril (noun)
a thin wire (usually tungsten) that is heated white hot by the passage of an electric current	one of many contractile filaments that make up a striated muscle fiber
a threadlike structure (as a chainlike series of cells)
the stalk of a stamen
a very slender natural or synthetic fiber