unity and unitypro what is different
Pro features:
Realtime Shadows
External Version Control Support
C/C++/Objective-C Plugins Support
Video Playback and Streaming
Fully Fledged Streaming with Asset Bundles
Script Access to Asset Pipeline
No Unity Splash Screen or Watermark
Is a partial list from the License.
I have answered this question before here:
http://answers.unity3d.com/questions/5505/pro-versus-free/5506#5506