otherworld vs spiritual world

otherworld

noun
  • A world beyond death; an afterlife. 

  • A world other than the everyday world. 

  • A mythical abode of otherworldly beings. 

spiritual world

noun
  • The afterlife. 

  • A metaphysical plane of existence parallel to the material world and occupied by spirits and other unearthly forces. 

How often have the words otherworld and spiritual world occurred in a corpus of books? (source: Google Ngram Viewer )