spy vs sleuth

spy and sleuth both are nouns.

Word	Noun	Adjective	Verb	Adverb
spy	Yes	No	Yes	No
sleuth	Yes	No	Yes	No

As verbs, spy and sleuth are synonyms defined as:

Other synonyms of spy include snoop, stag.

spy (noun)	sleuth (noun)
(military) a secret agent hired by a state to obtain information about its enemies or by a business to obtain industrial secrets from competitors	a detective who follows a trail
a secret watcher; someone who secretly watches other people

spy (verb)	sleuth (verb)
secretly collect sensitive or classified information; engage in espionage	watch, observe, or inquire secretly
watch, observe, or inquire secretly
catch sight of
catch sight of; to perceive with the eyes