The same question also applies to "how is WebEngage survey different from Qualaroo?"
Here's how we present our case:
1. WebEngage products can be "targeted" at certain audience segments based on a lot on in-built criterion like URL patterns, geography, cookies, traffic source etc - http://webengage.com/survey#targeting
2. Very recently, we took targeting to the next level by allowing application specific properties in our rule builder. Here's more - http://blog.webengage.com/2012/12/08/custom-targeting-launch...
3. WebEngage works via a JS widget code which is a one-time integration. All knobs and controls sit in the WebEngage Dashboard and for any new notifications or surveys that need to be run, customers don't need to change any code on their website.
4. Our reporting and analytics matches the best BI tools out there - http://webengage.com/survey#reports