postpone vs delay

postpone is not a noun while delay is a noun.

Word	Noun	Adjective	Verb	Adverb
postpone	No	No	Yes	No
delay	Yes	No	Yes	No

As verbs, delay is a hypernym of postpone; that is, delay is a word with a broader meaning than postpone:

postpone (noun)	delay (noun)
	the act of delaying; inactivity resulting in something being put off until a later time
	time during which some action is awaited

postpone (verb)	delay (verb)
hold back to a later time	cause to be slowed down or delayed
	stop or halt
	slow the growth or development of
	act later than planned, scheduled, or required