What's the difference between SQL Server Management Studio and the Express edition?

There are no differences in Management Studio. The differences are in the database engine LIMITATIONS! The engine is the same but it will deny you some features.

Import/Export wizard in the express edition can be found at: C:\Program Files\Microsoft SQL Server\90\DTS\Binn\DTSWizard.exe

If you dont have it, dowload it from Microsoft: http://go.microsoft.com/fwlink/?LinkId=65111

You could install the Microsoft SQL Server 2005 Express Edition Toolkit to get the cool toys, like the Import/Export wizard and the reports.

The profiler is not part of Management Studio. It is one more application that comes with the full version of the SQL Server. Even if you have it installed your express edition server engine will refuse to work with it.

Assuming you are talking about differences in the client tools and not the database engine, the only differences that I have found so far are the lack of reports and the profiler. In the full version, on the tree of objects you can right click and select from set of standard reports. In the Express version, that menu option is missing. The express version does not install the profiler.

Most of the High-Availability options are missing from the Express Edition. The Express editions are great for development purposes. Here's the comparison facts:

http://www.microsoft.com/sql/prodinfo/features/compare-features.mspx