Technically, a disciple (from the Latin discipulus, meaning “one who embraces the teachings of another”) is one who is learning from the master.
In Christianity, the term refers to any follower of Jesus’ teaching. We hear in the Gospel of Matthew 10:1, “And He called to Him His twelve disciples and gave them authority over unclean spirits, to cast them out, and to heal every disease and every infirmity.”
By the reference to these same twelve men as “apostles” in Matthew 10:2, it is clear that an apostle (from the Greek apostolos, meaning “someone who is sent; a messenger”) is also a special class of disciple. Some confusion may arise since the Gospels speak of the twelve both as disciples and as apostles, but also refers to seventy disciples distinct from the twelve apostles. Matthew and John were both Evangelists (Gospel Writers) and apostles (two of the twelve), but Mark and Luke, while also Evangelists, were only disciples (part of the seventy).
Apostles refer to the twelve men chosen by Jesus to be His immediate aides. Our Divine Lord instructed them during His public period of three years. After His ascension, the apostles went into the Upper Room with Mary and prayed for nine days for the coming of the Holy Spirit. After Pentecost, when the Holy Sprit descended upon them, they spoke and acted with confidence and assurance in teaching others what the Lord taught them. They became the leaders of the Church with Peter as the head of the apostles. They were ordained to the fullness of the priesthood by Jesus at the Last Supper when He said, “Do this in memory of Me.” By this command, they were ordained to continue the perpetual sacrifice of Jesus, but in the liturgical way of the Mass.
Today in the Church, the direct descendants of Peter and the apostles are the pope and the bishops. This is called Apostolic Succession. There has never been a break in this line right down to the 265th pope, Benedict XVI. In Matthew 10: 2–5 we have the twelve apostles’ names: “The names of the twelve apostles are these: first, Simon, who is called Peter, and Andrew his brother, James the son of Zebedee, and John his brother; Philip and Bartholomew; Thomas and Matthew the tax collector; James the son of Alphaeus, and Thaddaeus; Simon the Cananean, and Judas Iscariot, who betrayed him.”
Since Judas Iscariot eventually committed suicide, there was a need to replace him. Acts 1:26 says, “And they cast lots for them, and the lot fell on Matthias; and he was enrolled with the eleven apostles. Twelve is considered a biblical number. Just as there are twelve tribes of Israel, there are also twelve apostles. The honorary title by way of analogy was given to Mary Magdalene (apostle to the apostles) insofar as she was the first one at the empty tomb on Easter Sunday; she saw the Risen Christ Who instructed her to tell Peter and the other disciples that He had risen.
She had no pastoral office, however, and she was not at the Last Supper, either. Only the twelve apostles were there with Jesus.