buzz vs activity

buzz and activity both are nouns.

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

As nouns, activity is a hypernym of buzz; that is, activity is a word with a broader meaning than buzz:

buzz (noun)	activity (noun)
a confusion of activity and gossip	any specific behavior
sound of rapid vibration	the trait of being active; moving or acting rapidly and energetically
	an organic process that takes place in the body
	a process existing in or produced by nature (rather than by the intent of human beings)
	the state of being active
	(chemistry) the capacity of a substance to take part in a chemical reaction