Photoshop CS3 Extended includes all of the same features as Photoshop CS3 but adds a brand-new set of tools and capabilities for the integration of 3-D models, video and animation, and image measurement and analysis.
In CS3, Adobe did a very good job of making interface improvements without moving too far away from the familiar. Most of the new elements unique to Photoshop Extended are well integrated into the standard Photoshop and accessed from familiar tools such as the Layers panel or various menus.
Photoshop CS3 Extended can now import and manipulate 3-D objects, such as OBJ, 3DS, U3D (Acrobat 3D), KMZ (Google Earth), and COLLADA (XML files used most often for gaming) file formats. While these formats are all common and useful, the omission of DWG the most popular format for exchanging CAD (computer-aided design) models is glaring.