Gresham's Law vs rule

Gresham's Law and rule both are nouns.

Word	Noun	Adjective	Verb	Adverb
Gresham's Law	Yes	No	No	No
rule	Yes	No	Yes	No

As nouns, rule is a hypernym of Gresham's Law; that is, rule is a word with a broader meaning than Gresham's Law:

Gresham's Law: (economics) the principle that when two kinds of money having the same denominational value are in circulation the intrinsically more valuable money will be hoarded and the money of lower intrinsic value will circulate more freely until the intrinsically more valuable money is driven out of circulation; bad money drives out good; credited to Sir Thomas Gresham
rule: a rule or law concerning a natural phenomenon or the function of a complex system

Other hypernyms of Gresham's Law include principle.

Gresham's Law (noun)	rule (noun)
(economics) the principle that when two kinds of money having the same denominational value are in circulation the intrinsically more valuable money will be hoarded and the money of lower intrinsic value will circulate more freely until the intrinsically more valuable money is driven out of circulation; bad money drives out good; credited to Sir Thomas Gresham	measuring stick consisting of a strip of wood or metal or plastic with a straight edge that is used for drawing straight lines and measuring lengths
	a principle or condition that customarily governs behavior
	something regarded as a normative example
	a rule or law concerning a natural phenomenon or the function of a complex system
	a basic generalization that is accepted as true and that can be used as a basis for reasoning or conduct
	(mathematics) a standard procedure for solving a class of mathematical problems
	prescribed guide for conduct or action
	(linguistics) a rule describing (or prescribing) a linguistic practice
	directions that define the way a game or sport is to be conducted
	any one of a systematic body of regulations defining the way of life of members of a religious order
	dominance or power through legal authority
	the duration of a monarch's or government's power

Gresham's Law (verb)	rule (verb)
	keep in check
	decide with authority
	decide on and make a declaration about
	mark or draw with a ruler
	exercise authority over; as of nations
	be larger in number, quantity, power, status or importance
	have an affinity with; of signs of the zodiac