Whitehall vs civil service

Whitehall and civil service both are nouns.

Word	Noun	Adjective	Verb	Adverb
Whitehall	Yes	No	No	No
civil service	Yes	No	No	No

As nouns, civil service is a hypernym of Whitehall; that is, civil service is a word with a broader meaning than Whitehall:

Whitehall: the British civil service
civil service: government workers; usually hired on the basis of competitive examinations

Whitehall (noun)	civil service (noun)
the British civil service	government workers; usually hired on the basis of competitive examinations
a wide street in London stretching from Trafalgar Square to the Houses of Parliament; site of many government offices