Morok and Prystrit differences

The first thing to understand about the Morok is that it is a creature that is absolutely dangerous and yet mortal. Basically, it's an animal that, fortunately, hasn't been fully discovered by humans, and the Morok as a species has been described above. But let's talk about the possessed "other side" of this animal.

The Prystrὶt (пристріт - "curse") Morok is a Morok that was not buried and/or died an unnatural death. Moroks as highly intelligent animals are aware that their loved ones may not find their rest if they are not laid to rest respectfully. You could already read the "Rite of Forgotten" paragraph to see some details.
Now let's dwell on the promised and the creepiest part of it. 

How it happens

The scientific name for this type of creature is Canis Dirus Maledictus Serpentis, or Canis Dirus Maledictus Draconis if it was a winged type.

Prystrit is something between a ghost and a zombie of a deceased Morok. They are also made of flesh, their organs function and they still have feelings, but they have to endure terrible challenges to their bodies and suffer their harsh fate, staying that way until someone is merciful enough to create a special rite for them. Some Prystrits, however, begin to like what they have become and can see fear in the eyes of others as they emerge, bringing pain and suffering whenever they wish.  

Fortunately, Prystrits will not appear near humans unless they are too deep in the forest. But they can be summoned, and trust us, you don't want to mess up the summoning ritual.

Anatomy

Witnesses would describe Prystrits or Maras ("мара" (evil apparitions) if females) as a big canine-like serpent, which looks pretty dreadful, thanks to its long tongue with barbs on it and huge maw which reveals circling rows of teeth as if a huge snail's. So, be sure, this thing will maul you and make you suffer a long death if you're not going to be careful enough around them. 

After becoming Prystrit, these animal's fur fades in colour and their bodies may be screwed through with big holes. Sometimes fungus and moss may grow on them, which doesn't bother Prystrit at all. They already don't resemble slender and graceful creatures. Unlike Morok, Prystrit is tougher in build and smaller in size. The metamorphosis influences all their body.

General Appearance

Below you may see an obvious difference between Morok and Prystrit

Prytrits are bloodthirsty, cruel and generally more dangerous. Their pain threshold is much lower and they can endure much longer than their living relatives. However, they can still perform the same activities as Moroks. It is important to remember that some of the activities with extra requirements are specifically designed for Prystrits, which means that Moroks cannot do them. This also means that there are some activities that Prystrits can't do if they're only designed for Moroks.

Mostly, people who have bad intentions become their handlers. But if your handler is brave enough and trusts in themselves, they may try to tame this thing and maybe as well cancel its suffering. Deep inside, even though sometimes badly corrupted, every Prystrit wants to find its peace in eternity or through the Rite of Revival regain its life again.