use Modern::Perl;
my $line1= 'CABGFEBFA';
my $line2= 'DBFDDF';
say sort keys %{{map {$_ => 1} $line2 =~ /[$line1]/g}};
say sort keys %{{map {$_ => 1} $line1 =~ /[^$line2]/g, $line2 =~ /[^$line1]/g}};