#!/usr/bin/perl

use strict;
use warnings;

my %file1 = ( samp1 => 'stuff',
              samp2 => 'data',
              samp3 => 'info', 
              samp4 => 'foo',
              samp5 => 'bar',
              blah  => 'blah',
              brood => 'other' );  

my %file2 = ( samp1 => 'stuff',
              samp2 => 'diff',
              samp3 => 'blah',
              samp4 => 'foo',
              junk  => 'stuff',
              trash => 'other',
              samp5 => 'bar' );

my (@diff1, @diff2);

push @diff1, grep !$file2{$_}, keys %file1;
push @diff2, grep !$file1{$_}, keys %file2;