Ethics is a branch of science that concerns what ought to be.

Law is a branch of ethics that concerns with the use of violence in social interactions.

Morality is a personal code for people to adhere to.

The principle that legality does not equate morality is about separating what constitutes a law and what is moral.

A government can make a law stating that something illegal or legal. But that doesn't mean it's moral.

The natural law can also deem something legal, but it doesn't mean its moral.

That's what I was getting at.