mission vs missionary work

mission and missionary work both are nouns.

Word	Noun	Adjective	Verb	Adverb
mission	Yes	No	No	No
missionary work	Yes	No	No	No

As nouns, mission and missionary work are synonyms defined as:

mission and missionary work: the organized work of a religious missionary

mission (noun)	missionary work (noun)
a special assignment that is given to a person or group	the organized work of a religious missionary
an operation that is assigned by a higher headquarters
the organized work of a religious missionary
a group of representatives or delegates
an organization of missionaries in a foreign land sent to carry on religious work