I tried File::DirCompare and got some interesting results. It'll tell you which files differ, and, if $x and $y are the same directory, it'll simply return a prompt.

#!/usr/bin/perl

use strict;
use warnings;
use File::Basename;
use File::DirCompare;

my $dir1 = '/path/to/dir1';
my $dir2 = '/path/to/dir2';

File::DirCompare->compare($dir1, $dir2, sub {
  my ($a, $b) = @_;
  if (! $b) {
    printf "Only in %s: %s\n", dirname($a), basename($a);
    } elsif (! $a) {
    printf "Only in %s: %s\n", dirname($b), basename($b);
    } else {
    print "Files $a and $b differ\n";
    }
});
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