military music vs military march

military music and military march both are nouns.

Word	Noun	Adjective	Verb	Adverb
military music	Yes	No	No	No
military march	Yes	No	No	No

As nouns, military music and military march are synonyms defined as:

military music and military march: brisk marching music suitable for troops marching in a military parade

Other synonyms of military music include martial music.

military music (noun)	military march (noun)
brisk marching music suitable for troops marching in a military parade	brisk marching music suitable for troops marching in a military parade