palliative vs mitigatory

palliative is a noun but mitigatory is not a noun.

Word	Noun	Adjective	Verb	Adverb
palliative	Yes	Yes	No	No
mitigatory	No	Yes	No	No

As adjectives, palliative and mitigatory are synonyms defined as:

palliative and mitigatory: moderating pain or sorrow by making it easier to bear

Other synonyms of palliative include alleviative, alleviatory, lenitive, mitigative.

palliative (noun)	mitigatory (noun)
remedy that alleviates pain without curing

palliative (adjective)	mitigatory (adjective)
moderating pain or sorrow by making it easier to bear	moderating pain or sorrow by making it easier to bear