gangland vs Mafia

gangland and Mafia both are nouns.

Word	Noun	Adjective	Verb	Adverb
gangland	Yes	No	No	No
Mafia	Yes	No	No	No

As nouns, Mafia is a hyponym of gangland; that is, Mafia is a word with a more specific, narrower meaning than gangland:

gangland: underworld organizations
Mafia: a secret terrorist group in Sicily; originally opposed tyranny but evolved into a criminal organization in the middle of the 19th century

Other hyponyms of gangland include yakuza, Maffia, Sicilian Mafia, Black Hand, Camorra, crime syndicate, family, mob, syndicate.

gangland (noun)	Mafia (noun)
underworld organizations	a crime syndicate in the United States; organized in families; believed to have important relations to the Sicilian Mafia
	a secret terrorist group in Sicily; originally opposed tyranny but evolved into a criminal organization in the middle of the 19th century