What the difference between the Old Testament and the New Testament?

The "Old Testament"(written in Hebrew and Aramaic) is the term generally applied to the first 39 books of the Bible, before Jesus was born, containing the history of mankind, God's relationship with humanity from it's creation, and the foretelling of the coming of 'messiah' to save mankind.
The "New Testament"(written in Greek) is the name usually given to the last section of the Bible, containing Jesus' birth and life history, setting up of the Christian congregation, fulfillment of messianic prophecies and a fore gleam of mankind's future from God's perspective. See 'History' on discussion page.