I wouldn't get too hyped. I translated it as 2nd playthrough, but I don't know if that's the best translation. I am pretty sure it is like the stuff from previous chapters, where characters act differently if you had done a genocide run, then played a pacifist one.
I think that the Dev explained what each of the routes were once. IIRC,
True pacifist: you do not kill anyone, and recruit everyone as a friend.
Pacifist: you do not kill anyone, but you didn't recruit everyone either.
Neutral: you have killed before, but not everyone.
Genocide: ...you monster.
As for Bystander route, that was made in response to people complaining about the difficulty of the game, *cough* Iron Maiden *cough cough* Bystander route is essentially super easy mode, where battles are taken out. You get the H-scenes, but some of the story is unavailable and the ending is a joke. I believe it's called Spectator difficulty in Lv1VillagerA's machine translation.