circus tent vs big top

circus tent and big top both are nouns.

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

As nouns, circus tent and big top are synonyms defined as:

circus tent and big top: a canvas tent to house the audience at a circus performance

Other synonyms of circus tent include round top, top.

circus tent (noun)	big top (noun)
a canvas tent to house the audience at a circus performance	a canvas tent to house the audience at a circus performance