Observation
Part of speech: noun
Definition: The act of observing, and the fact of being observed. The act of noting and recording some event; or the record of such noting. A remark or comment. A judgement based on observing.
Example sentence: Not observation of a duty but liberty itself is the pledge that assures fidelity.
Observance
Part of speech: noun
Definition: The practice of complying with a law, custom, command or ruleThe custom of celebrating a holiday or similar occasionObservation or the act of watchingA rule governing a religious order, especially in the Roman Catholic church
Example sentence: To the house of a friend if you're pleased to retire, You must all things admit, you must all things admire; You must pay with observance the price of your treat, You must eat what is praised, and must praise what you eat.