Well, they appear to do the same, at least in the one-byte character range:

my $str = join '', map chr, 0 .. 255;

my $qm = quotemeta( $str);
( my $kyle = $str) =~ s/(\W)/\\$1/g;

my $quoted_qm = join '', $qm =~ /\\(.)/g;
my $quoted_kyle = join '', $kyle =~ /\\(.)/g;

printf "quotemeta: %d, kyle: %d (%s)\n",
    length $quoted_qm, 
    length $quoted_kyle,
    $quoted_qm eq $quoted_kyle ? "same" : "differernt";
[download]

That prints

quotemeta: 192, kyle: 192 (same)
[download]

Anno