spider web vs cobweb

spider web and cobweb both are nouns.

Word	Noun	Adjective	Verb	Adverb
spider web	Yes	No	No	No
cobweb	Yes	No	No	No

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

spider web: a web spun by spiders to trap insect prey
cobweb: a dense elaborate spider web that is more efficient than the orb web

Other hyponyms of spider web include funnel web, orb web, sheet web.

spider web (noun)	cobweb (noun)
a web spun by spiders to trap insect prey	a dense elaborate spider web that is more efficient than the orb web
a web resembling the webs spun by spiders	filaments from a web that was spun by a spider
	a fabric so delicate and transparent as to resemble a web of a spider