Earlier, I was posed with the question, "What is the difference between a disciple and an apostle?". Here's the answer...
The Catholic Encyclopedia says, "It is at once evident that in a Christian sense, everyone who had received a mission from God, or Christ, to man could be called 'Apostle.' In fact, however, it was reserved to those of the disciples who received this title from Christ." So it seems that while the 12 Apostles were disciples, not all disciples are apostles.
The word "disciple" comes from the Latin discipulus, or pupil. "Apostle" comes from the Greek word apostolos, or delegate. So, basically, anyone with a message from God is an Apostle. Thus its meaning, delegate, or messenger. Whereas, the title of disciple is given to one who accepted Jesus as teacher and followed him, "The Twelve Disciples".
For example; Others were appointed as apostles at later times and other purposes, including Paul, the apostle to the Gentiles, and Barnabas. Not just the twelve disciples. I believe- don't hold me to this- that there are 72 biblical apostles (or, holy men who accepted God's word, and acted in faith for God).