off-the-cuff vs ad-lib

off-the-cuff is not a noun while ad-lib is a noun.

Word	Noun	Adjective	Verb	Adverb
off-the-cuff	No	Yes	No	No
ad-lib	Yes	Yes	Yes	No

As adjectives, off-the-cuff and ad-lib are synonyms defined as:

Other synonyms of off-the-cuff include extemporaneous, extemporary, extempore, impromptu, offhand, offhanded, unrehearsed.

off-the-cuff (noun)	ad-lib (noun)
	remark made spontaneously without prior preparation

off-the-cuff (adjective)	ad-lib (adjective)
with little or no preparation or forethought	with little or no preparation or forethought
	said or done without having been planned or written in advance

off-the-cuff (verb)	ad-lib (verb)
	perform without preparation