In Nomine settings are often described with such terms as brightness and contrast.
Brightness refers to who's winning the War and whether that's a good thing for humanity. In a "standard" (angels good, demons bad) In Nomine configuration, therefore, "bright" means that Heaven is coming out on top. (In a "backwards" campaign, on the other hand, "bright" might mean that Hell's winning -- or even that both sides are tying each other down, leaving humans free to chart their own course!)
Contrast refers to just how different angels and demons are. In a very low contrast setting, they're just working in different political camps. In a very high contrast setting, they are so different that they might as well be different species, as different as they are.
Frequency refers to the frequency of celestials on Earth. Usually, this is the density of angels in a given population, which can range from basically everyone (high frequence) to a small group for the entire region (low frequency).
Intervention refers to the extent to which Superiors tolerate conspicuous intervention on the corporeal plane as part of the War.
It is safe to assume that the In Nomine universe, relative to our own, has its share of ghost stories and other folklore concerning supernatural intervention. Most of the time, it's more fun to assume that Superiors want to keep this war away from innocent eyes for a large variety of reasons; but at times it's much-needed to have an appearance to inspire people to pray and generate Essence.