weed killer vs atrazine

weed killer and atrazine both are nouns.

Word	Noun	Adjective	Verb	Adverb
weed killer	Yes	No	No	No
atrazine	Yes	No	No	No

As nouns, atrazine is a hyponym of weed killer; that is, atrazine is a word with a more specific, narrower meaning than weed killer:

weed killer: a chemical agent that destroys plants or inhibits their growth
atrazine: a synthetic compound derived from triazine that is widely used as an agricultural herbicide

Other hyponyms of weed killer include Agent Orange, linuron, paraquat, silvex, simazine, maleic hydrazide.

weed killer (noun)	atrazine (noun)
a chemical agent that destroys plants or inhibits their growth	a synthetic compound derived from triazine that is widely used as an agricultural herbicide