The Koran is deemed to be the exact word of God, not so the Bible, Old or New. 

It is an assemblage of books from different authors, times and places, which theologians and scholars have been poring over for centuries, trying to analyze them to distinguish what is history, what is literature and figurative, how translations from Hebrew, Aramaic, Greek, etc. may have affected the transmission over time, etc. Mainstream Christians have inherited that long tradition of interpretation and still reevaluate it.

That leaves a lot of leeway for interpretation, which is why you have so many different denominations and sects, and debate, and in many denominations you now have for example women priests and ministers and chaplains, etc.