Xavier Remington
A ghost is always directly a dead human while a demon is a fallen Angel who lives in a higher dimension. Although some evil humans are directly invited to join the demons, and many Angels may in fact be dead humans. Ghosts are generally harmless, and display themselves in visual, auditory, and olfactory ways. Demons on the other hand are deeply dangerous, and can physically hurt people, or even possess their minds, and bodies.
Ghosts
Various noxious stinks, tending to be sulfur in nature, are created by ghosts, poltergeists, demons, and other higher dimensional entities. Although gentle ghosts, usually relatives, tend to leave behind pleasant aromas such as perfume or cologne they wore in their time alive on Earth. The wretched fumes generally come into existence from a nefarious spirit whose sinister thoughts translate into dark metaphysical energy. That enchanted energy moves into our reality to become energy strings whose vibrations...
The innocence of the child mind, and their closeness to the afterlife(we all exist as spirits before we’re even born because the afterlife exists outside of time) via their closeness to their birth, allows small kids to see ghosts, and other higher dimensional entities that adults might not otherwise see. Most likely Grandma can’t let go of her life, and feels she has unfinished business. Until she willingly passes through the light into the heavenly planes...