Revenant is the broader historical idea of a bodily returning dead person. Vampire traditions are a more specific, regionally varied cluster later reshaped around blood drinking and literary rules.
Folklore
Vampire
Vampire is now a global fictional category, but the word entered Western European print through reports and debates about eastern and southeastern European returning-dead traditions. Historical accounts varied: suspected vampires might be blamed for illness, wasting, nightmares, or deaths in a household. The elegant, immortal blood drinker is largely a literary development rather than a complete description of village belief.
A revenant is a person believed to return from the grave in bodily form. Medieval European chronicles describe walking corpses that frightened relatives, spread sickness, or had to be restrained through exhumation and destruction. Unlike an insubstantial apparition, the revenant is usually physical. The term is now sometimes applied broadly, but its historical use should remain distinct from every culture’s beliefs about returning dead.