herald vs harbinger

herald and harbinger both are nouns.

Word	Noun	Adjective	Verb	Adverb
herald	Yes	No	Yes	No
harbinger	Yes	No	Yes	No

As nouns, herald and harbinger are synonyms defined as:

herald and harbinger: something that precedes and indicates the approach of something or someone

Other synonyms of herald include forerunner, precursor, predecessor.

As verbs, herald and harbinger are synonyms defined as:

Other synonyms of herald include announce, annunciate, foretell.

herald (noun)	harbinger (noun)
something that precedes and indicates the approach of something or someone	something that precedes and indicates the approach of something or someone
(formal) a person who announces important news

herald (verb)	harbinger (verb)
foreshadow or presage	foreshadow or presage
praise vociferously
greet enthusiastically or joyfully