Immortality is the state of possessing an infinite lifespan and an arresting aging process, meaning an immortal can live potentially forever without aging. This also grants immunity to all human diseases and viruses. Despite being able to life a potential eternal life, immortality does not grant protection from death through external forces, meaning that immortal beings can still be killed.
The Fae are a race of true immortal beings that can potentially live forever. They do not age as other living beings, instead their physical age is dependent on their their mental maturity and social status. Despite being immortal, the Fae can still be killed through external forces and possess the same weaknesses as ordinary humans.
Vampires gain immortality upon the completion of their transition. As undead beings, their bodies stop aging and they are immune to human diseases since they are not longer truly alive. Their biological functions are altered in the transition, as they no longer require the basic needs of the living and instead are dependent on blood.