As a matter of fact, there is! If you head over to the response section, you'll see a button at the top of the page that says Compare Mailings. It looks like this:
Click there, and you'll be taken to a page where you can select the mailings you like and then export the results. I think the Performance Summary export will be most helpful to you. Here's a help document that will walk you through the finer details.
I was the Product Manager that worked on this feature with my team, so I'd love to hear any feedback you have. Let us know if you need any more help.