use XML::DifferenceMarkup qw(make_diff);
use XML::LibXML;

my $old_xml = $ARGV[0];
my $new_xml = $ARGV[1];

my $parser = XML::LibXML->new();
$parser->keep_blanks(0);
my $d1 = $parser->parse_file($old_xml);
my $d2 = $parser->parse_file($new_xml);

my $dom = make_diff($d1, $d2);
print $dom->toString(1);