catch phrase vs catchword

catch phrase and catchword both are nouns.

Word	Noun	Adjective	Verb	Adverb
catch phrase	Yes	No	No	No
catchword	Yes	No	No	No

As nouns, catchword is a hypernym of catch phrase; that is, catchword is a word with a broader meaning than catch phrase:

Other hypernyms of catch phrase include phrase, motto, shibboleth, slogan.

catch phrase (noun)	catchword (noun)
a phrase that has become a catchword	a favorite saying of a group, organization or individual
	a word printed at the top of the page of a dictionary or other reference book to indicate the first or last item on that page