webworm vs fall webworm

webworm and fall webworm both are nouns.

Word	Noun	Adjective	Verb	Adverb
webworm	Yes	No	No	No
fall webworm	Yes	No	No	No

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

webworm: several gregarious moth larvae that spin webs over foliage on which they feed
fall webworm: a variety of webworm known as the fall webworm (Hyphantria cunea)

Other hyponyms of webworm include Hyphantria cunea, garden webworm, Loxostege similalis.

webworm (noun)	fall webworm (noun)
several gregarious moth larvae that spin webs over foliage on which they feed	a variety of webworm known as the fall webworm (Hyphantria cunea)