phalanx vs military group

phalanx and military group both are nouns.

Word	Noun	Adjective	Verb	Adverb
phalanx	Yes	No	No	No
military group	Yes	No	No	No

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

Other hypernyms of phalanx include force, military force, military unit.

phalanx (noun)	military group (noun)
any of the bones of the fingers or toes	a unit that is part of some military service
a body of troops in close array
any closely ranked crowd of people