word vs word of honor

word and word of honor both are nouns.

Word	Noun	Adjective	Verb	Adverb
word	Yes	No	Yes	No
word of honor	Yes	No	No	No

As nouns, word and word of honor are synonyms defined as:

Other synonyms of word include parole.

word (noun)	word of honor (noun)
a unit of language that native speakers can identify	a promise
a promise
information about recent and important events
a brief statement
an exchange of views on some topic
a secret word or phrase known only to a restricted group
a verbal command for action
a string of bits stored in computer memory

word (verb)	word of honor (verb)
put into words or an expression