I am trying to find a way to call notepad++ from command line with compare plugin showing the compare result providing I pass 2 files name which I want to compare.
T
There's a tool called NppCompareLoader doing exactly what you want. Simply drop it in the N++ installation folder. I'm using it since many years as a diff viewer for TortoiseSVN and TortoiseGit, thus you should certainly be able to call it right from command line.
/EDIT
Since the (unofficial) Compare-plug-in version 1.5.6.6 the additional loader mentioned above isn't required anymore. There's already one included in the plug-in. Here's the regarding change-log fragment: