cotton on vs get it

cotton on and get it both are verbs.

Word	Noun	Adjective	Verb	Adverb
cotton on	No	No	Yes	No
get it	No	No	Yes	No

As verbs, cotton on and get it are synonyms defined as:

Other synonyms of cotton on include catch on, get onto, get wise, latch on, tumble, twig.

cotton on (verb)	get it (verb)
understand, usually after some initial difficulty	understand, usually after some initial difficulty
	receive punishment; be scolded or reprimanded