Christ is the English term for the Greek word Χριστός ( Christós ), which literally means "The Anointed One." The word may be misunderstood by some as being the surname of Jesus due to the frequent juxtaposition of Jesus and Christ in the Christian Bible and other Christian writings. Often used as a more formal-sounding synonym for Jesus, the word is in fact a title, hence its common reciprocal use Christ Jesus, meaning The Anointed One, Jesus.
According to Matthew 1:20-21, an angel of the Lord appeared in a dream to Joseph (at the time Mary's fiancé), and told him that what was conceived in her is from the Holy Spirit, and that she would give birth to a son. The angel instructed Joseph to "give him the name Jesus - because he will save his people from their sins." The name Jesus, the Greek form of Joshua ( meaning the LORD saves).
Jesus and Christ refer to the same person whom Christians believe is God's son, who died on the cross to miraculously save his followers from their sins, and who rose from the dead on the third day after his death and later ascended into heaven where he sits at the "right hand of God the Father."
There are various names for the different depictions we encounter. In the west, Chirst the Teacher is depicted holding an open Gospel. Pantokrator, meaning Judge of All, is a name usually reserved for depictions when Chirst has the Gospel book closed, signifying that the time for repentance has ended. At times, icon appear with the Greek letters 'IC' and 'XC' in the upper corners, which are abbreviations for the Greek words for Jesus and Christ.