mourning vs bereavement

mourning and bereavement both are nouns.

Word	Noun	Adjective	Verb	Adverb
mourning	Yes	Yes	No	No
bereavement	Yes	No	No	No

As nouns, mourning and bereavement are synonyms defined as:

mourning and bereavement: state of sorrow over the death or departure of a loved one

mourning (noun)	bereavement (noun)
the passionate and demonstrative activity of expressing grief	state of sorrow over the death or departure of a loved one
state of sorrow over the death or departure of a loved one

mourning (adjective)	bereavement (adjective)
sorrowful through loss or deprivation