There are three kinds of packages:
The files with no architecture specified are BZip2 source tarballs (urbi-sdk-2.2.tar.bz2). Use them only if you are ready to compile Urbi SDK yourself.
GNU/Linux and Mac OS X packages are regular BZip2 tarballs.
The packages depend on the version of Visual C++ you use: 2005 or 2008.
Windows packages in "*.exe" contain an installer that installs both debug and release libraries, an UObject wizard for Visual C++, Gostai Editor and Gostai Console. Using the installers is strongly recommended.
If you know what you are doing, you might want to use the "*.zip" files. They come in two flavors: debug or release. They require that you have MS Visual C++ installed, or that you run "vcredist.exe" that can be found here.
|urbi-sdk-2.2-windows-x86-vcxx2008.exe||33M||Urbi SDK and documentation|
|urbi-sdk-2.2.tar.bz2||25M||Urbi SDK and documentation|
|urbi-sdk-2.2-linux-x86-gcc4.tar.bz2||15M||Urbi SDK and documentation|
|urbi-sdk-2.2-macos-x86-gcc4.tar.bz2||13M||Urbi SDK and documentation|
|urbi-sdk-2.2-linux-x86_64-gcc4.tar.bz2||12M||Urbi SDK and documentation|