Central deployment means that your Visual C++ DLLs are installed in the System32 directory. To centrally deploy your application, you can use one of the following:
•The VCRedist_architecture.exe command-line tool.
•Merge modules.
VCRedist_architecture.exe installs all libraries for the specific hardware platform. Merge modules, or .msm files, are simplified Windows Installer installation packages.
The main advantage of central deployment is emergency serviceability. If a critical security vulnerability is discovered, Microsoft automatically updates library files that are centrally-deployed.
Local deployment means that your application’s library files are installed in the application folder. To deploy your application locally, simply copy the executable file and its associated library files into a folder.
Different library versions can exist side-by-side because the filenames contain the version number (for example, version 10 of the CRT DLL is msvcr100.dll).
Unlike centrally-deployed libraries, local libraries are not updated automatically by Microsoft. If you decide to use local deployment, you should also implement your own method of updating libraries.