certificate of indebtedness vs obligation

certificate of indebtedness and obligation both are nouns.

Word	Noun	Adjective	Verb	Adverb
certificate of indebtedness	Yes	No	No	No
obligation	Yes	No	No	No

As nouns, certificate of indebtedness and obligation are synonyms defined as:

certificate of indebtedness and obligation: a written promise to repay a debt

Other synonyms of certificate of indebtedness include debt instrument.

certificate of indebtedness (noun)	obligation (noun)
a written promise to repay a debt	the social force that binds you to the courses of action demanded by that force
	a legal agreement specifying a payment or action and the penalty for failure to comply
	a written promise to repay a debt
	a personal relation in which one is indebted for a service or favor
	the state of being obligated to do or pay something