You can read the whole series here.
Jesus is coming into God’s presence, and Mark indicates it by saying Jesus falls to the ground. It’s Abrahamic. Luke doesn’t like this drastic picture: he has Jesus kneel—in control of himself always. Luke’s picture of Jesus in his trouble and finally his death is one that models the death of Christians in persecution. You see this in the death of Stephen.
Earlier, Mark reports that Jesus says (three different times) that he must suffer and die. But in prayer he now says, “And going a little further, he fell on the ground and prayed that, if it were possible, the hour might pass from him. ‘Abba, Father, all things are possible to thee; remove this cup from me.'” This seems illogical. Why is he praying for the trial to go away, when he’s already predicted that it will come?