In order to get a visual on the different levels of interaction of your contacts across multiple campaigns:
From the Reports menu (in the main navigation) choose either 'SMS Comparison' or 'Email Comparison'.
You will then see all your email / sms campaigns sent over the last 3 months. To see more campaigns, simply change the start date in the top of the screen and click the 'Go' button.
Select the tick box on the left hand side of each campaign that you would like to see in a graph, and click on the 'Graphically Compare Selected' button.
Hover over the bars to view the details. The image below is an example email comparison chart of 3 email messages.