A huge distinction between the two being WHO sent them. The one being sent by God, the other sent by boards of men.
Really? I was directly called of God the Holy Spirit to be a missionary. And I was not sent
by my mission board but
through my board and
from my local church. This dovetails very nicely with the story of Barnabas and Saul, sent by their local church and the Holy Spirit in Acts 13:1-4,
1 Now there were in the church that was at Antioch certain prophets and teachers; as Barnabas, and Simeon that was called Niger, and Lucius of Cyrene, and Manaen, which had been brought up with Herod the tetrarch, and Saul. {which...: or, Herod's foster brother}
2 As they ministered to the Lord, and fasted, the Holy Ghost said, Separate me Barnabas and Saul for the work whereunto I have called them.
3 And when they had fasted and prayed, and laid their hands on them, they sent them away.
4 So they, being sent forth by the Holy Ghost, departed unto Seleucia; and from thence they sailed to Cyprus.