foster child vs fosterling

foster child and fosterling both are nouns.

Word	Noun	Adjective	Verb	Adverb
foster child	Yes	No	No	No
fosterling	Yes	No	No	No

As nouns, foster child and fosterling are synonyms defined as:

Other synonyms of foster child include foster-child.

foster child (noun)	fosterling (noun)
a child who is raised by foster parents	a child who is raised by foster parents