envoy vs envoi

envoy and envoi both are nouns.

Word	Noun	Adjective	Verb	Adverb
envoy	Yes	No	No	No
envoi	Yes	No	No	No

As nouns, envoy and envoi are synonyms defined as:

envoy (noun)	envoi (noun)
a brief stanza concluding certain forms of poetry	a brief stanza concluding certain forms of poetry
a diplomat having less authority than an ambassador
someone sent on a mission to represent the interests of someone else