What is the difference between Divine Law and natural law?
In one sense there is no difference because both come from God. The two terms are used to distinguish how we know something.
Divine law is that which is revealed. We get it through Scripture or Sacred Tradition.
Natural law is that which we can reason to or realize on our own.
Divine Law would be something like "keep holy the sabbath." That is a law that comes to us directly from God in Scripture and which we would not otherwise know.
Natural Law would be something like "thou shall not murder." While it is in Scripture, we don't need Scripture to reveal it to us. Understanding that murder is immoral is something that we can reason to or realize on our own.