Comparing snapshots is a great way of gauging if changes made to a page are performing as expected; or comparing the results of the desktop version to the mobile version of the page.
From the snapshot reports dashboard, click on the snapshot name drop-down (in the top left-hand corner) OR on the horizontal dots to the far right-hand corner, select Compare Snapshots to reveal a list of all your snapshots.
Locate the snapshot you’d like to compare with and click Compare.
This will display both snapshots side by side for comparison.
