street child vs tiddler

street child and tiddler both are nouns.

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

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

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

street child (noun)	tiddler (noun)
a homeless child especially one forsaken or orphaned	a young person of either sex