use Fatal qw/open/;
my ( %h, %g );
open my $fh, '<', '/tmp/file1';
while ( defined ($_ = <$fh>)){
  /^([\d\.]+)/ and $h{$1}++;
}

open  $fh, '<', '/tmp/file2';
while ( defined ($_ = <$fh>)){
  /^([\d\.]+)/ and $g{$1}++;
}

my @k = keys %h;
delete @h{keys %g};
delete @g{@k};

print join "\n",( keys %h, keys %g );