A law is different from a theory how?

A scientific law describes the behavior of something that occurs. It is often described in mathematical relationships. For example the general law of gravitation describes the force between objects of various masses at various distances

A scientific theory, however, attempts to describe why something works. There are several theories of gravity, which attempt to explain why it occurs as it does.

Both Scientific Theories and Laws are based upon observation and experimentation. They can be disproved or modified to accommodate new discoveries, and must make predictions about future experiments and observations.