Scotland Yard vs police force

Scotland Yard and police force both are nouns.

Word	Noun	Adjective	Verb	Adverb
Scotland Yard	Yes	No	No	No
police force	Yes	No	No	No

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

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

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

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