They both match for me on:

This is perl 5, version 14, subversion 2 (v5.14.2) built for x86_64-li
+nux-thread-multi
[download]

Code:

use warnings;
use strict;

while (<DATA>) {
    print if /\s([#]\S)(.*)/;
}

__DATA__
123/; #<
456/; #< a comment
[download]

Output:

123/; #<
456/; #< a comment
[download]