national holiday vs public holiday

national holiday and public holiday both are nouns.

Word	Noun	Adjective	Verb	Adverb
national holiday	Yes	No	No	No
public holiday	Yes	No	No	No

As nouns, national holiday and public holiday are synonyms defined as:

national holiday and public holiday: authorized by law and limiting work or official business

Other synonyms of national holiday include legal holiday.

national holiday (noun)	public holiday (noun)
authorized by law and limiting work or official business	authorized by law and limiting work or official business