Meld:
Meld is a tool which allows the user to see the changes in, and merge between, either two files, two directories, or two files with a common ancestor.
Installation of Meld Diff Viewer
Open Ubuntu Software Center from Application menu and write meld in its search bar.
Open meld from command wndow by typing command as below.
$ meld
To test this software I create two different files original.txt and modified.txt as below.
Which describe much better result than diff command which is shown below.