requirement vs obligation

requirement and obligation both are nouns.

Word	Noun	Adjective	Verb	Adverb
requirement	Yes	No	No	No
obligation	Yes	No	No	No

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

requirement: something that is required in advance
obligation: the social force that binds you to the courses of action demanded by that force

Other hypernyms of requirement include duty, responsibility.

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

requirement: required activity
obligation: the social force that binds you to the courses of action demanded by that force

Other hypernyms of requirement include duty, responsibility.

requirement (noun)	obligation (noun)
something that is required in advance	the social force that binds you to the courses of action demanded by that force
required activity	a legal agreement specifying a payment or action and the penalty for failure to comply
anything indispensable	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