Maping parameter represents a constant value that You can define before running a session.A mapping parameter retains the same value throughout the entire session.

When you use the maping parameter ,U declare and use the parameter in a maping or maplet.Then define the value of parameter in a parameter file for the session.

Unlike a mapping parameter,a maping variable represents a value that can change throughout the session.The informatica server saves the value of maping variable to the

repository at the end of session run and uses that value next time you run the session.