The main difference is PowerCMS Builder allows you to install the PowerCMS system on multiple websites - think of it as a developer license. So you buy it once and use it on as many websites as you want to, you don't have to buy individual copies for individual sites like you do with Power CMS. 
Apart from the hike in price for the use of a developer's licence (which is justified), is this the only real difference? I ask because I still haven't bought it yet owing to other users reporting problems with it.
How important is the integration with Dreamweaver CS5? Unless I misunderstand (good chance of that!), you can't actually edit from within Dreamweaver.


