working principle vs working rule

working principle and working rule both are nouns.

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

As nouns, working principle and working rule are synonyms defined as:

working principle and working rule: a rule that is adequate to permit work to be done

working principle (noun)	working rule (noun)
a rule that is adequate to permit work to be done	a rule that is adequate to permit work to be done