DJG, check out, but DO NOT plaigarize:
http://www.cooke.net/~bradley/pink/mark.htm
and
http://earlychristianwritings.com/theories.html
The differences in the gospels is an amazingly interesting topic. I think the Matthew/Mark differences, IIRC, include:
1. Jesus asks who he is, answer is "son of god" - J-dude says "get back Satan"
2. Jesus asks who he is, answer is "son of god" - J-dud says "you are the rock on which I will build my temple."