poisoner vs killer

poisoner and killer both are nouns.

Word	Noun	Adjective	Verb	Adverb
poisoner	Yes	No	No	No
killer	Yes	No	No	No

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

Other hypernyms of poisoner include slayer.

poisoner (noun)	killer (noun)
someone who kills with poison	predatory black-and-white toothed whale with large dorsal fin; common in cold seas
	a difficulty that is hard to deal with
	someone who causes the death of a person or animal
	the causal agent resulting in death