Thank you. Yes, my question was about the moral difference, not the technical one, as other replies seem to interpret it. I understand that Harry had to have precautions in case his transfiguration fails at some point, but still, he destroyed the identity of his mentor without an immediate need to do so. He could have delayed irreversible actions until he has time to reflect. Rather un-Harry-like at this point in the story. Unless I'm missing something.