check out vs check up on

check out and check up on both are verbs.

Word	Noun	Adjective	Verb	Adverb
check out	No	No	Yes	No
check up on	No	No	Yes	No

As verbs, check out and check up on are synonyms defined as:

check out and check up on: examine so as to determine accuracy, quality, or condition

Other synonyms of check out include check, check into, check over, go over, look into, suss out.

check out (verb)	check up on (verb)
examine so as to determine accuracy, quality, or condition	examine so as to determine accuracy, quality, or condition
announce one's departure from a hotel
try to learn someone's opinions and intentions
record, add up, and receive payment for items purchased
withdraw money by writing a check
trace
be verified or confirmed; pass inspection