In the New Testament "Πνεῦμα" is used in the context of "the Holy Spirit," the malevolent/unclean spirits that Jesus casts out, and in the (presumably benevolent) spirit that John of Patmos finds himself in at the beginning of Revelation. Elsewhere the disciples are given the authority to cast out "δαιμόνια," and in yet a third case the disciples mistake(?) the risen Jesus for a "φάντασμά".
What were the differences between these three categories of supernatural being? Are these categories Christian only/developed by the New Testament authors, or are they referring to aspects of Jewish culture/folklore/spirituality which would have been familiar to everyday Judeans and Galileans in the time of Jesus?