Well, the main thing about the ghouls is the diet (Humans and ghouls, tea, coffee, water, ETC) and they have kagune’s.
A kagune is a ghoul’s predatory organ and functions as their weapon and claws. It is usually as red as blood, flexible like the flow of water, but firm and sturdy. When released, a ghoul’s physique is strengthened, they are more resilient, and their mobility heightens. A kagune is composed of Rc cells, which flow just like blood, can become as solid as teeth and can be described as “liquid muscles.” The Rc cells are released from an organ that ghouls have, piercing the skin, and the released Rc cells form the kagune. The kagune are voluntary muscles as ghouls can control them whenever they want and repeatedly harden and soften them at will. Kagune size depend on the Rc cells’ quality and quantity while the shape depends on the creativity and intellect of the user.
For example, Drem has a Ukaku,
An ukaku kagune is spread out like feathers and is released from the shoulder area, it specializes in high speed attacks, most of the users seeming to have highly enhanced speed. The kagune is lightweight and can be used to deliver high-speed attacks against an adversary, the primary method of attack is crystallizing their kagune to deliver a high speed torrent of spike-like projectiles, however whilst crystallized they are much stiffer and cannot be used for short range combat; at least one ukaku-type can generate powerful lightning-like bolts, a possible rare ability. While the kagune is suited both for short-distance and long-distance attacks, short-range is considered their weakness. They may use their kagune as a shield and several are capable of shaping them into sharp blades reminiscent of a koukaku to aid in close quarters. Many ukaku-types are able to increase the flexibility of their kagune for short-range combat, though this makes it ill-suited for their distinctive long-range attacks.
A koukaku kagune s released below the shoulder blade. Due to its high density of Rc cells, it is heavy and extremely robust, giving it the greatest sturdiness and making them very well suited for defense. Normally, they are generally shaped into armors or shields, but on the offense, they can be shaped like melee weapons such as drills, hammers, blades, and swords.
A rinkaku kagune has an appearance similar to scaled tentacles and is released at the back around the waist. A rinkaku wielder has powerful regenerative abilities and some could even survive the most critical of damage. Its peculiar appearance and structure yield a superior striking power and they excel in brute strength. Some rinkaku users are able to manipulate the shape of their kagune, such as changing its usual tentacle form into swords or claws.
This type’s regenerative power is a result of the Rc cells easily binding together. Their Rc cells are similar to liquid. However, this means that the binding force among the Rc cells are weak, therefore making the kagune very soft and easy to break. But because their Rc cells bind so easily, some rinkaku can bind their multiple tentacle-like kagune together to make a larger, stronger kagune. So far the number of tentacles that rinkaku users can create are from one to eight tentacles.
A bikaku kagune typically has a tail-like appearance and is released around the tail-bone/coccyx. It is good for medium-distance attacks and has decent offense, defense, and speed. Thus, they have no notable strengths or weaknesses like the kagune based on other Rc types, meaning the kagune itself is treated as a surprise “trump card.” So far, the number of tails a bikaku user can create are one to fourteen tails.
Although a ghoul’s healing ability is high, the healing of wounds tends to be delayed if the wounds are inflicted by a kagune. It is also evident that in order to counter a kagune in battle, one must also have a kagune, if not, at least something in relation to a kagune. Hence, ghoul investigators use kagune-based quinque as a tactical means to battle against ghouls.
The kagune’s appearance and the place of emergence on the body depend on the Rc type of the ghoul. There are four different Rc types: ukaku, koukaku, rinkaku, and bikaku. As a guideline, each type can characteristically subdue another type, although it may be different for two specific opponents. Each Rc type has a set of strengths and weaknesses, each one unique to its type. These are exploited by the CCG in the creation of the quinque and Q bullets.
Of course, we can edit these all we need ^^