Matching and Overlaying Plots

HI All, I have two different data sets that I am plotting on the same figure and I am trying to think of a way to determine how the plots of these two data sets match (display a matching percentage). I am not exactly sure if this is feasible in MATLAB. Thanks for the help!

[Image Analyst]

We can't help until we see a numerical example. What is "a data set"??? A list of (x,y) coordinates? An image?