my @list1 = qw/a b c d e f g/;
my @list2 = qw/a b c d e /;

my %one = ( a => 1, b => 1, c => 1 );
my %two = ( f => 1, g => 1 );

for my $key ( keys %one ) {
  if ( grep {$_ eq $key} @list1 and grep {$_ eq $key} @list2) { print "File 1 $key", $/ }
}

for my $key ( keys %two ) {
  unless ( grep {$_ eq $key} @list1 and grep {$_ eq $key} @list2 ) { 
    if ( grep {$_ eq $key} @list1 or grep {$_ eq $key} @list2 ) {
	  print "File 2 $key", $/;
    }
  }
}