circus vs big top

circus and big top both are nouns.

Word	Noun	Adjective	Verb	Adverb
circus	Yes	No	No	No
big top	Yes	No	No	No

circus (noun)	big top (noun)
a performance given by a traveling company of acrobats, clowns, and trained animals	a canvas tent to house the audience at a circus performance
a frenetic disorganized (and often comic) disturbance suggestive of a large public entertainment
an arena consisting of an oval or circular area enclosed by tiers of seats and usually covered by a tent
(antiquity) an open-air stadium for chariot races and gladiatorial games
a travelling company of entertainers; including trained animals