periodical vs publication

periodical and publication both are nouns.

Word	Noun	Adjective	Verb	Adverb
periodical	Yes	Yes	No	No
publication	Yes	No	No	No

As nouns, publication is a hypernym of periodical; that is, publication is a word with a broader meaning than periodical:

periodical (noun)	publication (noun)
a publication that appears at fixed intervals	the business of issuing printed matter for sale or distribution
	the act of issuing printed materials
	the communication of something to the public; making information generally known
	a copy of a printed work offered for distribution

periodical (adjective)	publication (adjective)
happening or recurring at regular intervals