A disciple is primarily a learner. This was also a term used to describe those who followed Jesus closely during his ministry. The implication here is that disciples of Jesus should be learners of his ways and truths. A disciple learns primarily by listening, watching and imitating and practicing what he or she sees. They were called disciples when they were learning from Jesus while he was there with them.
Many people think that disciple and apostle are one and the same.
The word for apostle has a very different connotation. It's always connected with doing God's work. A disciple is one who learns, an apostle is one who applies what he or she learns. The point of becoming a disciple is to go on to becoming an apostle. Therein lies the significance of discipleship.