seventies vs decade

seventies and decade both are nouns.

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

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

Other hypernyms of seventies include decennary, decennium.

seventies (noun)	decade (noun)
the time of life between 70 and 80	the cardinal number that is the sum of nine and one; the base of the decimal system
the decade from 1970 to 1979	a period of 10 years