What is the difference between the Holy Spirit and the Holy Ghost?

Over the centuries the translators of our Common Version English Bible have used the phrase "Holy Ghost" without any authority. The original Greek word is pneuma–spirit. In more recent times the Revised Version of the New Testament changed the word "Ghost" to read "Spirit."

There is no Scriptural reason to think of or speak of the holy Spirit as another God, distinct in personality from the Father and the Son. On the contrary, notice the fact that it was the Father's Spirit that was communicated to our Lord Jesus, as it is written, "The Spirit of the Lord God is upon me, because he hath anointed me to preach the Gospel." (Luke 4:18) Turning to the prophecy from which this quotation is made, we read there, in the Hebrew, "The Spirit of the Lord Jehovah is on me, because Jehovah hath anointed me to proclaim good tidings to the humble." (Isa. 61:1) And we read again, "And the Spirit of Jehovah shall rest upon him, the spirit of wisdom and understanding, the spirit of counsel and might, the spirit of knowledge and of reverence of Jehovah." (Isa. 11:2,3) Similarly the same Spirit in Christ is referred to as "The Spirit of Christ," the mind of Christ–"Let this mind be in you which was also in Christ Jesus our Lord." Phil. 2:5
 

The holy Spirit is variously defined in the Scriptures as:  "The Spirit of God," "The Spirit of Christ," "The Spirit of Holiness," "The Spirit of Truth," "The Spirit of a Sound Mind," "The Spirit of Liberty," "The Spirit of the Father," "The Holy Spirit of Promise," "The Spirit of Meekness," "The Spirit of Understanding," "The Spirit of Wisdom," "The Spirit of Glory," "The Spirit of Counsel," "The Spirit of Grace," "The Spirit of Adoption," "The Spirit of Prophecy."
These various titles, repeated many times, and used interchangeably, give us the full, proper assurance that they all relate to the same holy Spirit.

The Wilson Diaglott is a good source to see the Greek translation of the New Testament scriptures. You can view an on-line version of the Diaglott at:
https://archive.org/stream/emphaticdiaglott00wils#page