I'm talking about the genre, the teachings presented, and the authority on which they are based.
Teachings:
Most religions will lay down the usual moralizing about murder, adultery, and so forth. That is the surface. The Koran and the Bible present very different teachings about the nature of God, the way to attain a good hereafter, and other fundamental matters.
Genre:
The Bible comprises historical narratives (often first-hand accounts), biography, poetry, proverbs, theology, laws, prophecies, etc. The Koran is composed of the teachings on one man, Muhammed, who claimed to receive revelation from an angel. His accounts of other historical periods, based solely on the claim of angelic revelation, often contradict the much earlier writings by Moses, or by the Apostles.
Authority:
As stated, the Koran's authority flows from angelic revelation to one man. The Bible bases its truth on eyewitness accounts of history, personal contact with an incarnate God, and on divine revelation of various sorts.