street child vs child

street child and child both are nouns.

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

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

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

street child (noun)	child (noun)
a homeless child especially one forsaken or orphaned	a young person of either sex
	a human offspring (son or daughter) of any age
	an immature childish person
	a member of a clan or tribe