sixties vs decade

sixties and decade both are nouns.

Word	Noun	Adjective	Verb	Adverb
sixties	Yes	No	No	No
decade	Yes	No	No	No

As nouns, decade is a hypernym of sixties; that is, decade is a word with a broader meaning than sixties:

Other hypernyms of sixties include decennary, decennium.

sixties (noun)	decade (noun)
the time of life between 60 and 70	the cardinal number that is the sum of nine and one; the base of the decimal system
the decade from 1960 to 1969	a period of 10 years