bearer vs courier

bearer and courier both are nouns.

Word	Noun	Adjective	Verb	Adverb
bearer	Yes	No	No	No
courier	Yes	No	No	No

As nouns, courier is a hypernym of bearer; that is, courier is a word with a broader meaning than bearer:

Other hypernyms of bearer include messenger.

bearer (noun)	courier (noun)
a messenger who bears or presents	a person who carries a message
one of the mourners carrying the coffin at a funeral
the person who is in possession of a check or note or bond or document of title that is endorsed to him or to whoever holds it
someone whose employment involves carrying something