foreign mission vs legation

foreign mission and legation both are nouns.

Word	Noun	Adjective	Verb	Adverb
foreign mission	Yes	No	No	No
legation	Yes	No	No	No

As nouns, foreign mission and legation are synonyms defined as:

foreign mission and legation: a permanent diplomatic mission headed by a minister

foreign mission (noun)	legation (noun)
an organization of missionaries in a foreign land sent to carry on religious work	the post or office of legate
a permanent diplomatic mission headed by a minister	a permanent diplomatic mission headed by a minister