The Compare components dialog displays the differences detected when comparing two revisions of Footprint Items.
The dialog is accessed from the Explorer panel by browsing to the relevant folder, selecting the two Item-Revisions that you want to compare then right-clicking and choosing Operations » Compare from the context menu.
Differences between - lists the two compared footprints.
Layer tabs - inside the parentheses shows how many primitive objects have differences for each layer that was compared. Click on a tab allows you to browse the differences more thoroughly.
Component Primitives causing Differences for All Layers - lists the detected differences, categorized by Object Types, Identifiers, and Details.
Highlight Cell Density - use the slider bar to control the highlighted cells' density.
Image - the footprint is divided up into square cells and each cell has been analyzed for the differences. Cells where differences exist are shown in full color with the differences highlighted.