The languages that derive from Latin seem to use their variant of spiritus when they need to talk about disembodied life, especially in the religious context. In those same contexts, German uses Geist universally, both as a secularish term for the agent of haunting, and in the trinitarian sense -- heiliger Geist.
Since English seems to have been composed by luring other languages into dark alleys and robbing them of bits of grammar, English uses both Holy Ghost and Holy Spirit relatively interchangeably for identifying the member of the Trinity. I honestly don't see a problem for a non English speaker to ask what nuances of meaning there might be between two words that we often interchange. And I have no objection to a taxonomy we might choose to impose, if we propose to have a discussion where any difference has meaning (even a hypothetical meaning).