Early Christians avoided representing the body of Jesus on the cross until the end of the Roman persecution of Christians. During the persecutions the symbol of the cross could identify one as a Christian and result in their death. Christians sometimes disguised the cross as an anchor or combined the Greek letters for the name of Jesus forming a chi rho.
When the Roman Empire became Christian in the 4th century, the cross became public and very popular. During the 5th and 6th centuries, the cross became a highly glorified symbol. It was popular to decorate it with precious jewels to represent the victory achieved through the cross.
Emphasis on the suffering Savior in the late Middle Ages led to the popularity of the crucifix over the cross.
We often use the words cross and crucifix interchangeably, but there is a major difference. A crucifix is a cross with the body of Christ on it.