In nature swap, stats are swapped. In 'take half' stats are taken. In nature swap 50def would switch with 100 spdef, not 0 def and 150 spdef like you insinuated (which would be 'take 100%'). In nature swap, swapping slurpuff's atk and spatk would do nothing. In 'take half' it would make Slurpuff a strong special attacker (125spatk). So I have to disagree. They have less in common than Stat Exchange & Stat Preference.