Sounds like question from the list
There were a lot of enhancements introduced:
- Direct Discovery
- Alternate States
- Conditional Expressions and Dimensions
- Mobile platform
- and so on
it is a very long list... I suggest you to read Release Notes and try "What's new in QlikView 11?" application.
Hope this helps.
You can find the major differences in the first question on the QlikView 11 FAQ page on community.qlik.com/docs/DOC-2581.
Remember it is not just the differences, but also what you are missing out by not going to the more recent 11.20. Not only are you running an unsupported application as Onno pointed out, but there may also be compatibility issues with newer browsers and environments.