behest vs dictation

behest and dictation both are nouns.

Word	Noun	Adjective	Verb	Adverb
behest	Yes	No	No	No
dictation	Yes	No	No	No

As nouns, dictation is a hypernym of behest; that is, dictation is a word with a broader meaning than behest:

Other hypernyms of behest include bid, bidding, command.

behest (noun)	dictation (noun)
an authoritative command or request	speech intended for reproduction in writing
	an authoritative direction or instruction to do something
	matter that has been dictated and transcribed; a dictated passage