Downing Street vs authorities

Downing Street and authorities both are nouns.

Word	Noun	Adjective	Verb	Adverb
Downing Street	Yes	No	No	No
authorities	Yes	No	No	No

As nouns, authorities is a hypernym of Downing Street; that is, authorities is a word with a broader meaning than Downing Street:

Downing Street: the British government
authorities: the organization that is the governing authority of a political unit

Other hypernyms of Downing Street include government, regime.

Downing Street (noun)	authorities (noun)
the British government	the organization that is the governing authority of a political unit
a street of Westminster in London