initiation vs observance

initiation and observance both are nouns.

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

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

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

initiation (noun)	observance (noun)
the act of starting something for the first time; introducing something new	the act of observing; taking a patient look
an act that sets in motion some course of events	conformity with law or custom or practice etc.
wisdom as evidenced by the possession of knowledge	the act of noticing or paying attention
a formal entry into an organization or position or office	a formal event performed on a special occasion