bearer vs mourner

bearer and mourner both are nouns.

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

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

bearer: one of the mourners carrying the coffin at a funeral
mourner: a person who is feeling grief (as grieving over someone who has died)

Other hypernyms of bearer include griever, lamenter, sorrower.

bearer (noun)	mourner (noun)
a messenger who bears or presents	a person who is feeling grief (as grieving over someone who has died)
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