Development Tools
These components can be installed from the Development Tools category in the Select Components dialog box in Setup. To install development tools, choose a custom installation in the Setup Type screen. The Debugger Interface is an exception; it is included when you choose to install a typical installation.
Headers and Libraries
Installs the include (*.h) files and library (*.lib) files needed by a C developer to create programs that use OLE DB, ODBC, DB-Library, Open Data Services, SQL-DMO, Embedded SQL for C, and MS DTC. These files are installed in the \Program Files\Microsoft SQL Server\80\Tools\DevTools\Include and the \...\DevTools\Lib directories by default (shared tools location).
MDAC SDKs
Installs MDAC and XML Software Development Kits.
Backup/Restore API
Installs the header files, sample programs, and documentation required by software vendors to develop custom applications to back up and restore Microsoft SQL Server databases.
Debugger Interface
Installs an interface for stored procedure debugging.