killer vs causal agency

killer and causal agency both are nouns.

Word	Noun	Adjective	Verb	Adverb
killer	Yes	No	No	No
causal agency	Yes	No	No	No

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

killer: the causal agent resulting in death
causal agency: any entity that produces an effect or is responsible for events or results

Other hypernyms of killer include causal agent, cause.

killer (noun)	causal agency (noun)
predatory black-and-white toothed whale with large dorsal fin; common in cold seas	any entity that produces an effect or is responsible for events or results
a difficulty that is hard to deal with
someone who causes the death of a person or animal
the causal agent resulting in death