affidavit vs official document

affidavit and official document both are nouns.

Word	Noun	Adjective	Verb	Adverb
affidavit	Yes	No	No	No
official document	Yes	No	No	No

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

affidavit: written declaration made under oath; a written statement sworn to be true before someone legally authorized to administer an oath
official document: (law) a document that states some contractual relationship or grants some right

Other hypernyms of affidavit include instrument, legal document, legal instrument, testimony.

affidavit (noun)	official document (noun)
written declaration made under oath; a written statement sworn to be true before someone legally authorized to administer an oath	(law) a document that states some contractual relationship or grants some right