causal agent vs theurgy

causal agent and theurgy both are nouns.

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

As nouns, theurgy is a hyponym of causal agent; that is, theurgy is a word with a more specific, narrower meaning than causal agent:

causal agent: any entity that produces an effect or is responsible for events or results
theurgy: the effect of supernatural or divine intervention in human affairs

causal agent (noun)	theurgy (noun)
any entity that produces an effect or is responsible for events or results	white magic performed with the help of beneficent spirits (as formerly practiced by Neoplatonists)
	the effect of supernatural or divine intervention in human affairs