foster-daughter vs foster daughter

foster-daughter and foster daughter both are nouns.

Word	Noun	Adjective	Verb	Adverb
foster-daughter	Yes	No	No	No
foster daughter	Yes	No	No	No

As nouns, foster-daughter and foster daughter are synonyms defined as:

foster-daughter and foster daughter: someone who is raised as a daughter although not related by birth

foster-daughter (noun)	foster daughter (noun)
someone who is raised as a daughter although not related by birth	someone who is raised as a daughter although not related by birth