check out vs buy

check out is not a noun while buy is a noun.

Word	Noun	Adjective	Verb	Adverb
check out	No	No	Yes	No
buy	Yes	No	Yes	No

check out (noun)	buy (noun)
	an advantageous purchase

check out (verb)	buy (verb)
examine so as to determine accuracy, quality, or condition	accept as true
announce one's departure from a hotel	obtain by purchase; acquire by means of a financial transaction
try to learn someone's opinions and intentions	make illegal payments to in exchange for favors or influence
record, add up, and receive payment for items purchased	acquire by trade or sacrifice or exchange
withdraw money by writing a check	be worth or be capable of buying
trace
be verified or confirmed; pass inspection