journal vs periodical

journal and periodical both are nouns.

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

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

journal (noun)	periodical (noun)
the part of the axle contained by a bearing	a publication that appears at fixed intervals
a record book as a physical object
a periodical dedicated to a particular subject
a daily written record of (usually personal) experiences and observations
a ledger in which transactions have been recorded as they occurred

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