use strict;
use warnings;
use Data::Dumper;
my @AOA1 = (
 [2003,1],[2003,3],[2003,4],[2004,1]
);

my @AOA2 = (
 [2003,1],[2003,2],[2003,3],[2003,4],[2003,5],[2003,6],
 [2003,7],[2003,8],[2003,9],[2003,10],[2003,11],[2003,12],
 [2004,1],[2004,2]
);

my @diff = diff_AoA(\@AOA1, \@AOA2);
print Dumper \@diff;

sub diff_AoA {
 my @AofArray_refs = @_;       
 my %seen; 
  
 foreach my $array_ref( @AofArray_refs ) {
   foreach my $array ( @$array_ref ){
     my $key = join (",", map { qq("$_") } @$array );
     $seen{$key}{COUNT}++;
     $seen{$key}{ARRAY_REF} = [ @$array ];
   } 
 }  

 my @diff_array;

 foreach my $key ( keys %seen ) {  
   push @diff_array, $seen{$key}{ARRAY_REF} if $seen{$key}{COUNT} < 2;
  }
 return @diff_array; 
};