cause of death vs causal agent

cause of death and causal agent both are nouns.

Word	Noun	Adjective	Verb	Adverb
cause of death	Yes	No	No	No
causal agent	Yes	No	No	No

As nouns, causal agent is a hypernym of cause of death; that is, causal agent is a word with a broader meaning than cause of death:

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

Other hypernyms of cause of death include causal agency, cause.

cause of death (noun)	causal agent (noun)
the causal agent resulting in death	any entity that produces an effect or is responsible for events or results