In the First Eucharistic Controversy (ninth century), Paschasius Radbertus wrote a monograph arguing that the elements in communion were nothing less than the physical flesh and blood of Jesus. He was widely opposed, and another theologian, Ratramnus, replied. Everett Ferguson (Church History, I, 18.IV.D) summarizes his view:
Ratramnus opposed the realistic interpretation of the bread and wine, saying that the body and blood of Jesus Christ are present in a figure, not literally. The spiritual presence of the body of Christ is a mystery, available only to faith.
This sounds very much like the "spiritual presence" view of the Lord's supper, advocated by John Calvin and widely held today in Reformed theology.
Based on the writings of these two theologians, what are the major similarities and differences regarding their views on the nature of the elements in the Eucharist?