catnap vs catch a wink

catnap is a noun but catch a wink is not a noun.

Word	Noun	Adjective	Verb	Adverb
catnap	Yes	No	Yes	No
catch a wink	No	No	Yes	No

As verbs, catnap and catch a wink are synonyms defined as:

Other synonyms of catnap include nap.

catnap (noun)	catch a wink (noun)
sleeping for a short period of time (usually not in bed)

catnap (verb)	catch a wink (verb)
take a siesta	take a siesta