military ceremony vs observance

military ceremony and observance both are nouns.

Word	Noun	Adjective	Verb	Adverb
military ceremony	Yes	No	No	No
observance	Yes	No	No	No

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

Other hypernyms of military ceremony include ceremonial, ceremonial occasion, ceremony.

military ceremony (noun)	observance (noun)
a military custom performed in observance of some event or anniversary	the act of observing; taking a patient look
a formal ceremony performed by military personnel	conformity with law or custom or practice etc.
	the act of noticing or paying attention
	a formal event performed on a special occasion