The two names are currently interchangeable. The use of the name "Fallen Angels" acts as a sign of returning to our roots in a sense, but we are still known as Reapers. It would not be uncommon for us to be referred as both as names do not die out over night and it's going to be a slow and subtle transition. For the time being, either name will work to describe the population, but we are officially known as "Fallen Angels".