aging vs old

aging and old both are nouns.

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

aging (noun)	old (noun)
the organic process of growing older and showing the effects of increasing age	past times
acquiring desirable qualities by being left undisturbed for some time

aging (adjective)	old (adjective)
growing old	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