fibril vs cobweb

fibril and cobweb both are nouns.

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

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

Other hyponyms of fibril include barb, gossamer, chromatid, myofibril, myofibrilla, sarcostyle, rhizoid, hypha, paraphysis.

fibril (noun)	cobweb (noun)
a very slender natural or synthetic fiber	a dense elaborate spider web that is more efficient than the orb web
	filaments from a web that was spun by a spider
	a fabric so delicate and transparent as to resemble a web of a spider