Charles's law vs law of volumes

Charles's law and law of volumes both are nouns.

Word	Noun	Adjective	Verb	Adverb
Charles's law	Yes	No	No	No
law of volumes	Yes	No	No	No

As nouns, Charles's law and law of volumes are synonyms defined as:

Charles's law and law of volumes: (physics) the density of an ideal gas at constant pressure varies inversely with the temperature

Other synonyms of Charles's law include Gay-Lussac's law.

Charles's law (noun)	law of volumes (noun)
(physics) the density of an ideal gas at constant pressure varies inversely with the temperature	(physics) the density of an ideal gas at constant pressure varies inversely with the temperature