catchword vs watchword

catchword and watchword both are nouns.

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

As nouns, watchword is a hyponym of catchword; that is, watchword is a word with a more specific, narrower meaning than catchword:

Other hyponyms of catchword include catch phrase, catchphrase, mantra, battle cry, cry, rallying cry, war cry.

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