The only difference is the Book of Mormon... I think not. Though it is true that the book of Mormon does present a lot of new/different beliefs contrary to the Christian belief. There is more of a difference then just the Book. He needs to do his research.
The problem is, he is undeniably stubborn. It takes alot to get through to him.
Just a tip, don't force your religion on him. That's what pushes more people away from Christ than anything I can think of. So my advice is don't always go into a converstation with the mindset of converting. It takes time and self discovery. Take it little by little, day by day.
One day I believe the Lord will show himself to your friend. From there it is up to your friend to choose to except the Lord or not. Though I have faith it will all work out. It's always good to see people take interest in their friends spiritual life; true friendship
. I will be praying.