silvex vs weed killer

silvex and weed killer both are nouns.

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

As nouns, weed killer is a hypernym of silvex; that is, weed killer is a word with a broader meaning than silvex:

silvex: a herbicide that is effective in controlling woody plants but is toxic to animals
weed killer: a chemical agent that destroys plants or inhibits their growth

Other hypernyms of silvex include herbicide, weedkiller.

silvex (noun)	weed killer (noun)
a herbicide that is effective in controlling woody plants but is toxic to animals	a chemical agent that destroys plants or inhibits their growth