It is a good point and I also struggled with that bit somewhat. It is different in so many ways, have different symptoms, does not respond (as well) to the same

It is a good point and I also struggled with that bit somewhat. It is different in so many ways, have different symptoms, does not respond (as well) to the same medication, and affect different parts of the brain. The jump from there to "subtype" was not too logical for me ...