past vs recent

past is a noun but recent is not a noun.

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

past (noun)	recent (noun)
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 (adjective)	recent (adjective)
earlier than the present time; no longer current	new
of a person who has held and relinquished a position or office	of the immediate past or just previous to the present time

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