bereavement vs mourning

bereavement and mourning both are nouns.

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

As nouns, bereavement and mourning are synonyms defined as:

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

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

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