valediction vs valedictory oration

valediction and valedictory oration both are nouns.

Word	Noun	Adjective	Verb	Adverb
valediction	Yes	No	No	No
valedictory oration	Yes	No	No	No

As nouns, valediction and valedictory oration are synonyms defined as:

valediction and valedictory oration: a farewell oration (especially one delivered during graduation exercises by an outstanding member of a graduating class)

Other synonyms of valediction include valedictory, valedictory address.

valediction (noun)	valedictory oration (noun)
the act of saying farewell	a farewell oration (especially one delivered during graduation exercises by an outstanding member of a graduating class)
a farewell oration (especially one delivered during graduation exercises by an outstanding member of a graduating class)