Appointing of the Twelve Apostles

Scripture

Mark 3:16-19
Luke 6:13-16

Key Differences

The names of the disciples is slightly different.  In Mark the name Thaddeus is listed while Luke refers to him as Judas son of James.  The disciples are commonly referred to by different names which makes it difficult to tell them apart at times.  There are two key reasons for this.  First, Jesus gave some of them new names - Simon was referred to as Peter.  Secondly, the Jews spoke Aramaic, the language of their captivity in Babylon.  The scholars would have been able to understand Hebrew as this was what their scriptures were originally written in.  The common language of the world was Greek which would have been spoken by anyone who did business outside of Israel.  Often names mean the same thing but are translated differently if they are referred to by their Greek or Aramaic name.

Mark tells us that James and John are brothers and are referred to as the sons of thunder.  Luke lets us know that Andrew is a brother of Peter.

Additional Commentary

Aside from the name discrepancies in these two lists, Matthew is referred to as Levi elsewhere and Thomas is called Didymus.