Competitors report returns domains that are ranking for a large number of keywords related to the researched query.
Common Keywords - number of keywords related to the researched query.
All Keywords - total number of the domain's keywords
Visibility - domain visibility score
Changing the List of Competitors
You can edit the competitor’s list by adding or removing competitors. Click on Change the List of Competitors box, enter a new competitor or remove an existing one, and click on Apply.