File comparison

cmp filename1 filename2

cmp -- is one of the four principle UNIX file comparison utilities.

   It compares 2 files, and returns the positions where they differ.

comm -options filename1 filename2

comm -- This utility is used in comparing two files, produces three

   columns of output. The first contains lines unique to the
   first file, the second, lines unique to the second, and the
   third column, lines common to both files. By placing the
   numbers [1], [2], and/or [3] in the [options] position, any
   one (or more) of these columns can be suppressed.