LiveCycle is known by a few different things. LiveCycle ES1 was knowns as version 8.0 and LiveCycle ES2 is known as version 9.0. Version 9.1 is actually a service pack for LiveCycle ES2. If you like, I would look at the What's new document for LiveCycle ES2 so you can see what is different in that release (http://www.adobe.com/go/learn_lc_whatsNew_9).