nineties vs years

nineties and years both are nouns.

Word	Noun	Adjective	Verb	Adverb
nineties	Yes	No	No	No
years	Yes	No	No	No

nineties (noun)	years (noun)
the time of life between 90 and 100	a late time of life
the decade from 1990 to 1999	a prolonged period of time
the decade from 1890 to 1899	the time during which someone's life continues