Boffo babble part duo:
So I was sitting around staring at the wall, as I am won't to do, when a thought crosses my mind: what the hell are the demons and angels, anyway? Well. I've figured out a few things, but they won't tell me everything (damn secretive bastards).

First thing is that they're old. Very old. As far as anyone knows, they don't die of old age; they can commit suicide, which basically means they violently disrupt the bonds that tie them to reality- any reality, since they operate and several different ones. This usually involves a complicated ritual or a lot of energy; in Lilian/Leala's case, it involved a little of both, and it still caused a very messy tear in the spaces between this world and all the other ones out there. That's how the Shade got to Dei- Catenus felt her die and took advantage of the resulting hole in the fabric of reality. They can also die if hit by their opposite; for an angel, demon thrown lightning or ice, and for a demon, angelfire. Things like stars exploding have been known to take them down as well, but only if they're weak and young.

Age equates to power, so Lucifer, being one of the oldest angels alive, is also one of the most powerful. Catenus is young compared to Queen Lilith, but old compared to the rest of the population of demons. Leala was older than him by several millenia. Radueriel is about the same age as Leala; Shateiel, Leiliel, Metatron, and Sadriel are all very old. Powers differ between individuals, but it's a given that an angel will in general be able to fling fire around; they are creatures of light and heat and chaos; the demons are their polar opposite, controlling cold, darkness, and order. Angels also play around with things like sound, speed and nuclear radiation (I haven't quite figured that one out yet, either), while the demons get electricity and weather patterns. This is something of a generalization, since there are angels of darkness, order, ice, etc...just as there are demons who are most comfortable dealing in fire and brimstone. Regardless of the demon or angel's chosen area of expertise, if hit by something from the other side hard enough, they'll explode quite violently.

They are shapeshifters, before all else. In their natural forms, they resemble Vandergraff generators (I know I spelled that wrong), only not. You see Lucifer's true form in the beginning of chapter six, in the garden- he's just a spinning ball of light. The demons are the same, only darkness. In essence, the are pure energy, sheer power, that just up and decided to go screwing with the universe one day. The angels can take more damage, more negative energy to their systems, than the demons can stand positive energy.

In general the angels are tougher, but they pay for this with slightly diminished mental capacity...most of them are masculine, or choose to take masculine forms when shapeshifting. Not all, but there are definitely more male or masculine-androgenous angels than there are female. They are chaotic- it comes from constantly giving off energy all the time, and many of them act perpetually wired. Fallen angels tend to be exceptions to this, but they're a whole 'nother kettle of fish. Angels have more power at their disposal than the demons do, but it has often been proved that sometimes a little finesse is more effective than destroying planets when it comes to getting your point across.

Demons are creatures of ritual- they are orderly and self-contained, and what they lack in terms of sheer power compared to the angels, they make up in terms of scheming, sneaky, well thought out plans. I mean, Catenus has been planning this whole fiasco for millenia, ever since Radueriel was felled; about six thousand years ago, in terms of the story. Most demons choose female or female-androgenous forms, but again, there are exceptions.