myofibrilla vs fibril

myofibrilla and fibril both are nouns.

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

As nouns, fibril is a hypernym of myofibrilla; that is, fibril is a word with a broader meaning than myofibrilla:

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

Other hypernyms of myofibrilla include filament, strand.

myofibrilla (noun)	fibril (noun)
one of many contractile filaments that make up a striated muscle fiber	a very slender natural or synthetic fiber