the way 5 see it, there are two types of AH. There are the what WOULD have happened, and the what COULD have happened. the what would have happened use a lot of logic and historical statistics to back up the most likely scenarios. The what could have happened scenarios tend to rely on the writer's imagination, an example being Man in the High Castle. what could have happened scenarios also tend to include more character development while what would have happened scenarios really immerse you into the world that the writer has created.