thrips vs onion thrips

thrips and onion thrips both are nouns.

Word	Noun	Adjective	Verb	Adverb
thrips	Yes	No	No	No
onion thrips	Yes	No	No	No

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

thrips: any of various small to minute sucking insects with narrow feathery wings if any; they feed on plant sap and many are destructive
onion thrips: injurious to onion plants and sometimes tobacco

Other hyponyms of thrips include Frankliniella fusca, tobacco thrips, onion louse, Thrips tobaci.

thrips (noun)	onion thrips (noun)
any of various small to minute sucking insects with narrow feathery wings if any; they feed on plant sap and many are destructive	injurious to onion plants and sometimes tobacco