bicentennial vs bicentenary

bicentennial and bicentenary both are nouns.

Word	Noun	Adjective	Verb	Adverb
bicentennial	Yes	Yes	No	No
bicentenary	Yes	Yes	No	No

As adjectives, bicentennial and bicentenary are synonyms defined as:

bicentennial and bicentenary: of or relating to or completing a period of 200 years

As nouns, bicentennial and bicentenary are synonyms defined as:

bicentennial and bicentenary: the 200th anniversary (or the celebration of it)

bicentennial (noun)	bicentenary (noun)
the 200th anniversary (or the celebration of it)	the 200th anniversary (or the celebration of it)

bicentennial (adjective)	bicentenary (adjective)
of or relating to or completing a period of 200 years	of or relating to or completing a period of 200 years