bereaved vs grieving

bereaved is a noun but grieving is not a noun.

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

As adjectives, bereaved and grieving are synonyms defined as:

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

bereaved (noun)	grieving (noun)
a person who has suffered the death of someone they loved

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