street urchin vs gamine

street urchin and gamine both are nouns.

Word	Noun	Adjective	Verb	Adverb
street urchin	Yes	No	No	No
gamine	Yes	No	No	No

As nouns, gamine is a hyponym of street urchin; that is, gamine is a word with a more specific, narrower meaning than street urchin:

street urchin: a child who spends most of his time in the streets especially in slum areas
gamine: a homeless girl who roams the streets

Other hyponyms of street urchin include gamin, street arab, throwaway.

street urchin (noun)	gamine (noun)
a child who spends most of his time in the streets especially in slum areas	a girl of impish appeal
	a homeless girl who roams the streets