Boo Hags are a special kind of Night Hag that are found in modern American folklore, especially that of "hoodoo", envisioned as horrific demons resembling flayed old women they could wear the skin of others in order to disguise themselves as human but during the hours of night would fly into homes and drain people of life, often "riding" them and causing similar disturbances as the Night Hags.
Boo Hags prefer to keep victims alive but are known to engage in some horrific acts, most notably flaying a victim alive if they struggle too much, this is another distinguishing feature between them and the more ghostly Night Hags (who do not tend to physically mutilate victims).