mourning vs bereaved

mourning and bereaved both are nouns.

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

As adjectives, mourning and bereaved are synonyms defined as:

Other synonyms of mourning include bereft, grief-stricken, grieving, sorrowing.

mourning (noun)	bereaved (noun)
the passionate and demonstrative activity of expressing grief	a person who has suffered the death of someone they loved
state of sorrow over the death or departure of a loved one

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