cmp
-Byte by byte comparision performed for two files comparision and displays the first mismatch byte.
-cmp returns the 1st byte and the line no of the fileone to make the changes to make the fileone identical to filetwo.
-Directory names can not be used.
diff
-Indicates the changes that are to be done to make the files identical.
-returns the text of filetwo that is different from filetwo.
-Directory names can be used