installation vs observance

installation and observance both are nouns.

Word	Noun	Adjective	Verb	Adverb
installation	Yes	No	No	No
observance	Yes	No	No	No

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

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

installation (noun)	observance (noun)
the act of installing something (as equipment)	the act of observing; taking a patient look
a building or place that provides a particular service or is used for a particular industry	conformity with law or custom or practice etc.
a formal entry into an organization or position or office	the act of noticing or paying attention
	a formal event performed on a special occasion