working rule vs regulation

working rule and regulation both are nouns.

Word	Noun	Adjective	Verb	Adverb
working rule	Yes	No	No	No
regulation	Yes	Yes	No	No

As nouns, regulation is a hypernym of working rule; that is, regulation is a word with a broader meaning than working rule:

Other hypernyms of working rule include rule.

working rule (noun)	regulation (noun)
a rule that is adequate to permit work to be done	the act of controlling or directing according to rule
	the act of bringing to uniformity; making regular
	a principle or condition that customarily governs behavior
	an authoritative command
	(embryology) the ability of an early embryo to continue normal development after its structure has been somehow damaged or altered
	the state of being controlled or governed

working rule (adjective)	regulation (adjective)
	prescribed by or according to regulation