mid-sixties vs sixties

mid-sixties and sixties both are nouns.

Word	Noun	Adjective	Verb	Adverb
mid-sixties	Yes	No	No	No
sixties	Yes	No	No	No

As nouns, mid-sixties and sixties are synonyms defined as:

mid-sixties (noun)	sixties (noun)
the time of life between 60 and 70	the time of life between 60 and 70
	the decade from 1960 to 1969