street child vs nestling

street child and nestling both are nouns.

Word	Noun	Adjective	Verb	Adverb
street child	Yes	No	No	No
nestling	Yes	No	No	No

As nouns, nestling is a hypernym of street child; that is, nestling is a word with a broader meaning than street child:

Other hypernyms of street child include child, fry, kid, minor, nipper, shaver, small fry, tiddler, tike, tyke, youngster.

street child (noun)	nestling (noun)
a homeless child especially one forsaken or orphaned	young bird not yet fledged
	a young person of either sex