How are scientific fact and a law different?

A fact can be either a general observation (water boils at 100o Celsius under normal atmospheric pressure) or a specific observation (this glass contains 100 milliliters of water). A law of nature is some illuminating general observation that helps us to understand how the universe works. The classic example of this is Newton's Law of Universal Gravitation - which remains very useful, even though it has been subject to revision by Einstein.