command post vs HQ

command post and HQ both are nouns.

Word	Noun	Adjective	Verb	Adverb
command post	Yes	No	No	No
HQ	Yes	No	No	No

As nouns, HQ is a hypernym of command post; that is, HQ is a word with a broader meaning than command post:

command post: military headquarters from which a military commander controls and organizes the forces
HQ: the military installation from which a commander performs the functions of command

Other hypernyms of command post include headquarters, military headquarters.

command post (noun)	HQ (noun)
military headquarters from which a military commander controls and organizes the forces	the military installation from which a commander performs the functions of command