Creatures and Monsters
A creature is defined as something that naturally inhabits the world. This could be something as simple as a boar, wolf or bear that is encountered during a natural event in its life such as when the animal is hunting or when player characters decide to sleep in a cave otherwise occupied. Most creatures are not necessarily out to inflict harm, but most have a strong instinct for survival and will not give up their home or pelt without a fight.
Of course, the term creature can also be used to describe other non-humanoid entities with intelligence equal or greater than a player character, such as dragons. Depending on whom you ask, Dragons are not necessarily monsters.
A monster is, on the other hand, something unnatural. It may have begun life as something natural, or maybe merely takes the shape of something familiar to fool its prey, but it is generally out to cause harm to whatever it encounters. Monsters are often driven by a particular desire, whether that be to simply kill as many adventurers as possible or a mission with a set of behaviors defined by the Storyteller. A monster generally serves an entity, position or will; having very little of their own ambition.
Both Creatures and Monsters are created the same way as player characters, but can be simplified down to just the core skills and values needed. Storytellers may also choose between adding the skill levels in character qualities to the Health pool as normal, or to add the total number of skill points spent to build the entity in order to present a more significant challenge.