conservation of matter vs law of conservation of matter

conservation of matter and law of conservation of matter both are nouns.

Word	Noun	Adjective	Verb	Adverb
conservation of matter	Yes	No	No	No
law of conservation of matter	Yes	No	No	No

As nouns, conservation of matter and law of conservation of matter are synonyms defined as:

conservation of matter and law of conservation of matter: a fundamental principle of classical physics that matter cannot be created or destroyed in an isolated system

Other synonyms of conservation of matter include conservation of mass, law of conservation of mass.

conservation of matter (noun)	law of conservation of matter (noun)
a fundamental principle of classical physics that matter cannot be created or destroyed in an isolated system	a fundamental principle of classical physics that matter cannot be created or destroyed in an isolated system