wiseacre vs wise guy

wiseacre and wise guy both are nouns.

Word	Noun	Adjective	Verb	Adverb
wiseacre	Yes	No	No	No
wise guy	Yes	No	No	No

As nouns, wiseacre and wise guy are synonyms defined as:

wiseacre and wise guy: an upstart who makes conceited, sardonic, insolent comments

Other synonyms of wiseacre include smart aleck, weisenheimer, wisenheimer.

wiseacre (noun)	wise guy (noun)
an upstart who makes conceited, sardonic, insolent comments	an upstart who makes conceited, sardonic, insolent comments