age vs old

age and old both are nouns.

Word	Noun	Adjective	Verb	Adverb
age	Yes	No	Yes	No
old	Yes	Yes	No	No

age (noun)	old (noun)
how long something has existed	past times
a time of life (usually defined in years) at which some particular qualification or power arises
a late time of life
an era of history having some distinctive feature
a prolonged period of time

age (adjective)	old (adjective)
	of long duration; not new
	(used especially of persons) having lived for a relatively long time or attained a specific age
	skilled through long experience
	(used for emphasis) very familiar
	excellent
	just preceding something else in time or order
	belonging to some prior time