Fusion point or melting point:

                          When a substance is changed from a solid to a liquid state by adding heat, the process is called melting or fusion.

                           The temperature at which a solid start melting is called its fusion point or melting point.

Freezing point:

                  The temperature at which a substance is changed from liquid to solid state is called the freezing point. However, the freezing point of a substance is the same as its melting point.