Black Hand vs gangland

Black Hand and gangland both are nouns.

Word	Noun	Adjective	Verb	Adverb
Black Hand	Yes	No	No	No
gangland	Yes	No	No	No

As nouns, gangland is a hypernym of Black Hand; that is, gangland is a word with a broader meaning than Black Hand:

Black Hand: a secret terrorist society in the United States early in the 20th century
gangland: underworld organizations

Other hypernyms of Black Hand include gangdom, organized crime.

Black Hand (noun)	gangland (noun)
a secret terrorist society in the United States early in the 20th century	underworld organizations