debenture vs legal document

debenture and legal document both are nouns.

Word	Noun	Adjective	Verb	Adverb
debenture	Yes	No	No	No
legal document	Yes	No	No	No

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

debenture: a certificate or voucher acknowledging a debt
legal document: (law) a document that states some contractual relationship or grants some right

Other hypernyms of debenture include instrument, legal instrument, official document.

debenture (noun)	legal document (noun)
a certificate or voucher acknowledging a debt	(law) a document that states some contractual relationship or grants some right
the ability of a customer to obtain goods or services before payment, based on the trust that payment will be made in the future