Scotland Yard vs constabulary

Scotland Yard and constabulary both are nouns.

Word	Noun	Adjective	Verb	Adverb
Scotland Yard	Yes	No	No	No
constabulary	Yes	No	No	No

As nouns, constabulary is a hypernym of Scotland Yard; that is, constabulary is a word with a broader meaning than Scotland Yard:

Scotland Yard: the detective department of the metropolitan police force of London
constabulary: the force of policemen and officers

Other hypernyms of Scotland Yard include law, police, police force.

Scotland Yard (noun)	constabulary (noun)
the detective department of the metropolitan police force of London	the force of policemen and officers