Code Compare tools add value to the Review Assistant when used together. That's why they sell it in the code review package. You can save money on both tools by purchasing bundles.
Review Assistant Review Assistant is a code review plug-in of Visual Studio. This tool can help you create review requests and respond to them without leaving Visual Studio.
Code Compare A tool for comparing and merging different files and folders, it integrates all popular source code control systems: TFS, SVN, Git, Mercurial, and Perforce.