observance vs observant

observance is a noun but observant is not a noun.

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

observance (noun)	observant (noun)
the act of observing; taking a patient look
conformity with law or custom or practice etc.
the act of noticing or paying attention
a formal event performed on a special occasion

observance (adjective)	observant (adjective)
	paying close attention especially to details
	(of individuals) adhering strictly to laws and rules and customs
	quick to notice; showing quick and keen perception