This is the stand-alone Object Model Installer for TFS 2013 Update 4. This may be used for developing applications that integrate with TFS 2013 Update 4.
This is the same Object Model included with the Visual Studio and Team Explorer SKU, in a stand-alone package. This OM will allow applications to connect to a TFS 2013 Update 4 server, without the need for Visual Studio or Team Explorer being installed on the machine. Proper licensing and CALs are still required.