The Spirit of Christ and the Holy Ghost
1. The Spirit of Christ is given to every person born upon the earth--to help them tell good from evil.
2. Manifestations of the Holy Ghost can be given to people from time to time (as an investigator being taught by the missionaries might have the Holy Ghost witness to them of its truthfulness, etc.).
3. The Gift of the Holy Ghost (the companionship of the Holy Ghost to be with you all the time if you live worthily.) This comes only to baptized and confirmed members of the Church of Jesus Christ of Latter-day Saints.
One way to think of the Holy Ghost is like a magnifying glass--magnifying the Spirit of Christ.
One BYU Professor used this analogy: The Spirit of Christ given to every person born upon the earth is like a flashlight--very important and can help us out of the darkness. It can grow dimmer or brighter in different individuals. The Gift of the Holy Ghost is like a floodlight or turning on the Stadium lights--gives us much more light with which to discern and see by.
"Every individual born to earth is given a detecting capability, a divinely appointed gift to distinguish truth from error. We call it our conscience, God calls it the Spirit of Christ. When we properly use this gift, we are naturally drawn to truth and repelled from error."
Richard G. Scott (November 1979 Ensign, page 70)
"Conscience warns us as a friend before it punishes us as a judge."
Quoted by Thomas S. Monson, BYU Fireside
March , 1993