bicentenary vs bicentennial

bicentenary and bicentennial both are nouns.

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

As adjectives, bicentenary and bicentennial are synonyms defined as:

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

As nouns, bicentenary and bicentennial are synonyms defined as:

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

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

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