Immortality is simply the absence of the aging process in a biological entity. In the world of the supernatural there are a number of known Immortal beings that don’t age, and live forever. These include special humans, vampires, mermaids, demigods, and various creatures with some level of higher dimensional lineage. In the future all humankind will become Immortal courtesy of technological advancements! Unfortunately Immortality doesn’t mean complete invulnerability from death. Depending on the variety of Immortal they might be killed by any means, or only in a certain set of limited scenarios. Especially if advanced healing is present. In this way they are mortal at heart. If for no other reason they would meet their maker someday when their atomic structures eventually come unglued in the final trillions of years the Universe experiences it’s own swan song. Although the Macroverse, and this Omniverse may live on forever without end, this particular parallel Universe will someday cease existing unless some awesome higher dimensional power intervenes!
Amortality refers to not only being Immortal but also having the inability to die. Generally these are beings never born into the physical Universe, and therefore were technically never alive to begin with Although this doesn’t mean they’re invincible. They may be weakened, badly injured, or bested in a fight by certain limited means. Despite that they still can’t be killed by any means. This even includes beheading, or complete incineration of their physical bodies! If the Universe came to an end they would theoretically just float about the dark five dimensional void of nothingness for all eternity. It’s virtually unheard of for a biological being to be Amortal since most of the time we’re talking about enchanted entities from higher dimensions of reality or special parallel dimensions. These amazing amortals include Angels, Demons, Jinn, and Poltergeists along with virtually all Gods, and Goddesses. However there are isolated circumstances where these metaphysical energy entities may take a pure physical form, on purpose, or against their will, and in essence downgrade to Immortal status. A state where their spiritual form is solidified in their physical body. If extinguished they would be blinked from existence without any higher dimensional soul to fall back on. Some of these supernatural beings also possess the power to bestow Amortal status on anyone they so choose. Certainly Genies, aka caged Jinn, are able to grant wishes of amortality, and even invincibility to an extent! Some ultra powerful human practitioners of magic may give themselves, or others, immortality along with amortality to an extent!
Technically the human soul in all it’s various higher dimensional incarnations is Amortal as well. Which means outside this Multiverse we’re all Amortal! This includes Ghosts, Human Angels, Travelers, and Human Gods since our destiny is to eventually evolve, and ascend to Omniverse God status, and beyond!