Visual Studio Comparison Tools is an extension for Visual Studio which uses external tools to compare files, folders and clipboard. Features: Comparing two files, selecting folders for comparison from the solution explorer and comparing (and merging) clipboard to a file or selected area in a file. By default uses Beyond Compare if found, then WinMerge (http://winmerge.org/) and if neither is found uses VSDiff to compare files. Tested to work with Beyond Compare 3 and 4.
Source: Visual Studio Comparison Tools – Visual Studio Marketplace