In the second picture, he seems to be over jumping the jump a bit, which is natural for green jumpers. Also his knees could be more "tucked up" to his chest, but then again, if hes a green jumper its all natural. For being new to jumping, he looks brilliant. But why so high? If you leave the jumps smaller it will give him time to fine tune his skills. He will eventuall be able to level out how high to jump and soon learn to tuck up when jumping.
But for being green, he looks well on his way :)