dictation vs behest

dictation and behest both are nouns.

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

As nouns, behest is a hyponym of dictation; that is, behest is a word with a more specific, narrower meaning than dictation:

Other hyponyms of dictation include countermand, order, charge, commission, direction, commandment, injunction, open sesame.

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