I get asked this A LOT!
There are some key differences between 3ds Max and 3ds Max Design
3ds Max Design is intended for architecture and visualization, the tutorials and movies that are included show typical applications and scenarios for these customers. In addition, 3ds Max Design contains Exposure™ lighting analysis technology, which is designed specifically for architecture and visualization work flows. To learn more about Exposure lighting analysis, refer to the 3ds Max Design Help.
The tutorials and movies included with 3ds Max demonstrate 3D pipelines typically employed by artists and animators in films, games and television-related fields. In addition, 3ds Max ships with the SDK which can be used to add your own plug-ins to your 3ds Max pipeline. The only difference that you will notice during the install procedure is that you cannot install the SDK with 3ds Max Design.
It is possible to install both 3ds Max and 3ds Max Design on the same machine—a unique serial number and product key for each product is required to activate the software so that you can run the products beyond the 30-day trial period.