years vs nineties

years and nineties both are nouns.

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

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