watchword vs catchword

watchword and catchword both are nouns.

Word	Noun	Adjective	Verb	Adverb
watchword	Yes	No	No	No
catchword	Yes	No	No	No

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

Other hypernyms of watchword include motto, shibboleth, slogan.

watchword (noun)	catchword (noun)
a secret word or phrase known only to a restricted group	a favorite saying of a group, organization or individual
a slogan used to rally support for a cause	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