doer vs causal agent

doer and causal agent both are nouns.

Word	Noun	Adjective	Verb	Adverb
doer	Yes	No	No	No
causal agent	Yes	No	No	No

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

doer: a person who acts and gets things done
causal agent: any entity that produces an effect or is responsible for events or results

Other hypernyms of doer include causal agency, cause.

doer (noun)	causal agent (noun)
a person who acts and gets things done	any entity that produces an effect or is responsible for events or results