military group vs military force

military group and military force both are nouns.

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

As nouns, military group and military force are synonyms defined as:

military group and military force: a unit that is part of some military service

Other synonyms of military group include force, military unit.

military group (noun)	military force (noun)
a unit that is part of some military service	a unit that is part of some military service