activity vs agency

activity and agency both are nouns.

Word	Noun	Adjective	Verb	Adverb
activity	Yes	No	No	No
agency	Yes	No	No	No

As nouns, agency is a hyponym of activity; that is, agency is a word with a more specific, narrower meaning than activity:

activity (noun)	agency (noun)
any specific behavior	to have the ability to produce a particular effect or achieve an end
the trait of being active; moving or acting rapidly and energetically	an administrative unit of government
an organic process that takes place in the body	a business or organization that provides a particular service, especially the mediation of transactions between two parties
a process existing in or produced by nature (rather than by the intent of human beings)	the state of serving as an official and authorized delegate or agent
the state of being active	the state of being in action or exerting power
(chemistry) the capacity of a substance to take part in a chemical reaction