urchin vs nestling

urchin and nestling both are nouns.

Word	Noun	Adjective	Verb	Adverb
urchin	Yes	No	No	No
nestling	Yes	No	No	No

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

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

urchin (noun)	nestling (noun)
poor and often mischievous city child	young bird not yet fledged
	a young person of either sex