Feature-wise the biggest addition in Catalyst 14.6 is Eyefinity 3.0, which introduces support for mixed resolutions. This means you'll be able to mix screens with different horizontal and/or vertical pixel lines, you'll be able to configure them in fill mode, fit mode, and expand mode.
Although AMD team does not actually call it Eyefinity 3.0, they do referrer to it as ‘third major update to multi-display solution’. Eyefinity 2.0 already brought some flexibility to multi-display configurations. The latest update will allow you to mix displays with different resolutions. Imagine you have one 1600p display and two 1080p. It works great in Windows, but games do not support it (at least in fullscreen mode). To overcome this problem AMD developed a new technology that will allow you to either expand the area which is displayed, fill it on each display (which pretty much what we have today), or fit it to adequate proportions.Source: VideoCardz
New Eyefinity will also let you align the bezels the way you want it (top, center, or bottom). Eyefinity group can now be created with a single click, and it doesn’t matter what resolutions your monitors are using.