brevet vs written document

brevet and written document both are nouns.

Word	Noun	Adjective	Verb	Adverb
brevet	Yes	No	Yes	No
written document	Yes	No	No	No

As nouns, written document is a hypernym of brevet; that is, written document is a word with a broader meaning than brevet:

brevet: a document entitling a commissioned officer to hold a higher rank temporarily (but without higher pay)
written document: writing that provides information (especially information of an official nature)

Other hypernyms of brevet include document, papers.

brevet (noun)	written document (noun)
a document entitling a commissioned officer to hold a higher rank temporarily (but without higher pay)	writing that provides information (especially information of an official nature)

brevet (verb)	written document (verb)
promote somebody by brevet, in the military