Many are called to be disciples, but only a few are chosen to be apostles.

Now it came to pass in those days that He went out to the mountain to pray, and continued all night in prayer to God. And when it was day, He called His disciples to Himself;  and from them He chose twelve whom He also named apostles: Simon, whom He also named Peter, and Andrew his brother; James and John; Philip and Bartholomew; Matthew and Thomas; James the son of Alphaeus, and Simon called the Zealot; Judas the son of James, and Judas Iscariot who also became a traitor.
Luke 6:12-16 -NKJV