An important difference is that Python 3.0 arrived soon, while it took ages for a complete Perl 6 release to be available. That is, if you didn't want to learn or use Python 2.x because it was soon going to be obsolete, you already had a working alternative; but if you didn't want to learn or use Perl 5.x because it was soon going to be obsolete, for a significant amount of time Perl 6 wasn't an option.