military academy vs academy

military academy and academy both are nouns.

Word	Noun	Adjective	Verb	Adverb
military academy	Yes	No	No	No
academy	Yes	No	No	No

As nouns, academy is a hypernym of military academy; that is, academy is a word with a broader meaning than military academy:

military academy (noun)	academy (noun)
an academy for training military officers	a learned establishment for the advancement of knowledge
	a secondary school (usually private)
	a school for special training
	an institution for the advancement of art or science or literature