A scientific law is description of observed phenomenon or process. But it do not tells why that process occurs or exists. The explanation the phenomenon is scientific theory.
It never changes.
They brought out by the means of keen observations.
Legal law:
A body of rules of conduct approved and enforced by the government or of and over a certain the territory.
They are subjected change.
They are brought out by the governing bodies in accordance to their convenience of rule and for the betterment of the people and society.
Scientific Law is proven by the demoonstration of an irrefutable fact - for instance The Law of Gravity. Legal law refers to the body of man-made statutes passed by mankind in order to govern and control civilization and humanity.