The Summary module displays the overall comparison of the involved domains: you'll see the factors listed on the left and each domain's stats for each factor. The best result for each factor will be highlighted in green so that you could easily spot the domain that has the most winning characteristics. At the bottom, you will also see the Overall rating calculated for the displayed domains (from 1 star to 5).
You can Add / Remove Domains from the comparison at any point. To see any factor's description, you can hover over the factor and click on the info icon for a tooltip.
The results for Top TLDs, Top Countries and Anchors are expandable: if you hover over the result and click on the context menu icon, you'll see the list of records involved.
Now that you've gained an understanding of how your domain compares to those of your competitors', proceed to explore link intersections.