headquarters vs ACLANT

headquarters and ACLANT both are nouns.

Word	Noun	Adjective	Verb	Adverb
headquarters	Yes	No	No	No
ACLANT	Yes	No	No	No

As nouns, ACLANT is a hyponym of headquarters; that is, ACLANT is a word with a more specific, narrower meaning than headquarters:

headquarters: (plural) a military unit consisting of a commander and the headquarters staff
ACLANT: a major strategic headquarters of NATO located in the United States; is under the authority of the North Atlantic Council

Other hyponyms of headquarters include Allied Command Atlantic, ACE, Allied Command Europe.

headquarters (noun)	ACLANT (noun)
the military installation from which a commander performs the functions of command	a major strategic headquarters of NATO located in the United States; is under the authority of the North Atlantic Council
(usually plural) the office that serves as the administrative center of an enterprise
(plural) a military unit consisting of a commander and the headquarters staff