mandatory vs mandatary

mandatory and mandatary both are nouns.

Word	Noun	Adjective	Verb	Adverb
mandatory	Yes	Yes	No	No
mandatary	Yes	No	No	No

As nouns, mandatory and mandatary are synonyms defined as:

mandatory (noun)	mandatary (noun)
a territory surrendered by Turkey or Germany after World War I and put under the tutelage of some other European power until they are able to stand by themselves	the recipient of a mandate
the recipient of a mandate

mandatory (adjective)	mandatary (adjective)
required by rule