Matthew : to show Jesus as the Son of David-- the kingly Messiah who fulfills prophecy. Mark : to show Jesus as the suffering Son of Man sent to serve , not to be served. Luke : to show Jesus as the Savior of the world who has compassion for all human beings. John : to show Jesus as the Son of God , thw word made flesh , who provides eternal life to all who believe in Him.
I'm not sure if this would be classified as a feature, but more of a fact, but did you know that the four main gospels weren't even written by the people they were named for? They were written by their followers.
The Gospel of Matthew was written primarily for the Jews and emphasized how Jesus fulfilled the prophecies of a kingly Messiah. Mark was written primarily for Roman or Gentile Christians, so it includes few Old Testament prophecies, and explains many Jewish words and customs. Jesus is portrayed in Mark as the Divine Servant. Luke was also written primarily for Gentile believers, as it also explains Jewish customs and uses Greek names. Luke set out to write an orderly narrative of the life of Jesus, and presented Jesus as the Son of Man, emphasizing His full humanity. John's Gospel emphasizes Jesus as the Son of God, and includes more of Jesus' revelations about Himself than any of the other gospels. It also gives a much more detailed picture of the events during Jesus' last days.http://www.gotquestions.org/harmony-Gospels.html