armed service vs military service

armed service and military service both are nouns.

Word	Noun	Adjective	Verb	Adverb
armed service	Yes	No	No	No
military service	Yes	No	No	No

As nouns, armed service and military service are synonyms defined as:

armed service and military service: a force that is a branch of the armed forces

Other synonyms of armed service include service.

armed service (noun)	military service (noun)
a force that is a branch of the armed forces	land tenure by service in the lord's army
	a force that is a branch of the armed forces