filial duty vs obligation

filial duty and obligation both are nouns.

Word	Noun	Adjective	Verb	Adverb
filial duty	Yes	No	No	No
obligation	Yes	No	No	No

As nouns, obligation is a hypernym of filial duty; that is, obligation is a word with a broader meaning than filial duty:

filial duty: duty of a child to its parents
obligation: the social force that binds you to the courses of action demanded by that force

Other hypernyms of filial duty include duty, responsibility.

filial duty (noun)	obligation (noun)
duty of a child to its parents	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