UPDATED ...
I want to call kdiff from the Console application. Therefore, I create two files and want to compare them at the end of my program:
string diffCmd = string.Format("{0} {1}", Logging.FileNames[0], Logging.FileNames[1]); // diffCmd = D:\vdenisenko\DbHelper\DbHelper\bin\Debug\Reports\16_Nov 06_30_46_DiscussionThreads_ORIGIN.txt D:\vdenisenko\DbHelper\DbHelper\bin\Debug\Reports\16_Nov 06_30_46_DiscussionThreads_ORIGIN.txt System.Diagnostics.Process.Start(@"C:\Program Files (x86)\KDiff3\kdiff3.exe", diffCmd); //specification is here http://kdiff3.sourceforge.net/doc/documentation.html
It launches the kdiff3 tool, but something is wrong with the file names or the command ... Could you look at the screenshot and say what is wrong? 
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