It may prove easier if you consider the Holy Ghost as the Holy Spirit and saved yourself confusing the two. It's quite easy. [Right. Yes. If you're Bertie.]

I think being dead, and disembodied are part of the criteria. But a ghost... perhaps it's nothing more than a snapshot of a moment, repeating itself. Or a soul trapped between the earth and Heaven, because it had business to finish. Perhaps it is a moment of tragedy so powerful it lasts beyond it's instant.

I don't think anyone here are ghosts. They're not disembodied. They are certainly in a form of afterlife, but not in the same way as a ghost.