When I was doing diff, I was getting result if it differs or not.
Then, by looking in to diff man page I found the solution.
Unicode file can be treated as normal file and we can find difference.
Without option
santosh-test:~ # diff unicode.txt unicode.txt.Backup.1
Files unicode.txt and unicode.txt.Backup.1 differ
With option
santosh-test:~ # diff unicode.txt unicode.txt.Backup.1 -a
32c32
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