millenary vs 1000

millenary and 1000 both are nouns.

Word	Noun	Adjective	Verb	Adverb
millenary	Yes	Yes	No	No
1000	Yes	Yes	No	No

As nouns, 1000 is a hypernym of millenary; that is, 1000 is a word with a broader meaning than millenary:

millenary: a sum or aggregate of one thousand (especially one thousand years)
1000: the cardinal number that is the product of 10 and 100

Other hypernyms of millenary include chiliad, G, grand, K, M, one thousand, thou, thousand, yard.

millenary (noun)	1000 (noun)
a sum or aggregate of one thousand (especially one thousand years)	the cardinal number that is the product of 10 and 100
a span of 1000 years
the 1000th anniversary (or the celebration of it)

millenary (adjective)	1000 (adjective)
relating to or consisting of 1000	denoting a quantity consisting of 1,000 items or units
of or relating to the doctrine of the millennium