envoy vs emissary

envoy and emissary both are nouns.

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

As nouns, envoy and emissary are synonyms defined as:

envoy and emissary: someone sent on a mission to represent the interests of someone else

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