I think it's easier to listen to them to see the difference but,
There are different strains of blackened death metal, the more melodic style typically from Sweden with bands such as Dissection, Dawn, Sacramentum (although I consider their first and imo best album, straight up black metal), Unanimated, Necrophobic, etc.
Then there is stuff like Ackercocke, Behemoth, Belphegor, etc, which I'm not really a fan of. Seems to be death metal with some black metal influences.
War/bestial black metal is typically far more aggressive with much rawer production and full of chaotic blasting.
Stuff like:
Blasphemy - Fallen Angel of Doom
Beherit -The Oath of Black Blood
Antichrist - Sacrament of Blood
Teitanblood - Seven Chalices
Proclamation - Advent of Black Omen
Archgoat -The Light-Devouring Darkness
By no means does this cover everything, but it's just to give you an idea. As I said at the start, you should just listen to them to get a feel for the differences.