past times vs past

past times and past both are nouns.

Word	Noun	Adjective	Verb	Adverb
past times	Yes	No	No	No
past	Yes	Yes	No	Yes

As nouns, past times and past are synonyms defined as:

Other synonyms of past times include yesteryear.

past times (noun)	past (noun)
the time that has elapsed	a verb tense that expresses actions or states in the past
	the time that has elapsed
	a earlier period in someone's life (especially one that they have reason to keep secret)

past times (adjective)	past (adjective)
	earlier than the present time; no longer current
	of a person who has held and relinquished a position or office

past times (adverb)	past (adverb)
	so as to pass a given point