barb vs fibril

barb and fibril both are nouns.

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

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

barb: one of the parallel filaments projecting from the main shaft of a feather
fibril: a very slender natural or synthetic fiber

Other hypernyms of barb include filament, strand.

barb (noun)	fibril (noun)
one of the parallel filaments projecting from the main shaft of a feather	a very slender natural or synthetic fiber
a subsidiary point facing opposite from the main point that makes an arrowhead or spear hard to remove
the pointed part of barbed wire
an aggressive remark directed at a person like a missile and intended to have a telling effect

barb (verb)	fibril (verb)
provide with barbs