periodic law vs law of nature

periodic law and law of nature both are nouns.

Word	Noun	Adjective	Verb	Adverb
periodic law	Yes	No	No	No
law of nature	Yes	No	No	No

As nouns, law of nature is a hypernym of periodic law; that is, law of nature is a word with a broader meaning than periodic law:

periodic law: (chemistry) the principle that chemical properties of the elements are periodic functions of their atomic numbers
law of nature: a generalization that describes recurring facts or events in nature

Other hypernyms of periodic law include law.

periodic law (noun)	law of nature (noun)
(chemistry) the principle that chemical properties of the elements are periodic functions of their atomic numbers	a generalization that describes recurring facts or events in nature