No, different characters. As for Sora, as I said, he's the first boss you defeat. It's never explored what that means for Sora, but he never resurfaces in the game. It's been a long time since I've watched it, but I would judge Sora's death or release based on his appearance or non-appearance in the .hack//UNISON OVA (which I don't remember, 'cause it's been so long and not a big issue for me).