The result is different for plot over line and feature edges

Hi, I need some help on the filters “plot over line” and “feature edges”. I have some data on a rectangle, and I would like to plot the data on one side of the rectangle. I think there are two ways to do that: we could use directly plot over line to plot the data on the side of the rectangle. But also, we could first extract data on boundaries, then plot the data in some other software or use “plot data” in paraview. However, when I tried to do that, the resulting graphs are different for these two ways, which confuses me. Could anyone help to explain why is this? Thanks!