reward vs honorarium

reward and honorarium both are nouns.

Word	Noun	Adjective	Verb	Adverb
reward	Yes	No	Yes	No
honorarium	Yes	No	No	No

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

Other hyponyms of reward include bounty, premium, blood money, guerdon, meed.

reward (noun)	honorarium (noun)
an act performed to strengthen approved behavior	a fee paid for a nominally free service
benefit resulting from some event or action
the offer of money for helping to find a criminal or for returning lost property
a recompense for worthy acts or retribution for wrongdoing
payment made in return for a service rendered

reward (verb)	honorarium (verb)
strengthen and support with rewards
act or give recompense in recognition of someone's behavior or actions
bestow honor or rewards upon