Moveit planning inaccurate?

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Hello there,

I'm trying to save robot positions to xml files, load them into an interface and make plans through the stored states.

However, i just loaded a pose into my program, planned and executed a Trajectory, but it is incredibly inaccurate! I have this information in my Code:

position: 
  x: 0.25001175875
  y: 0.00521729120018
  z: 1.4402651584
orientation: 
  x: -2.02521411299e-05
  y: 1.32614594766e-06
  z: -0.999999995194
  w: 9.59202891974e-05

store it in arrays xyz and q
then i use :

robot_commander = moveit_commander.MoveGroupCommander('arm') //arm is the 6DOF Group of my Robot
robot_commander.set_position_target(xyz)
robot_commander.set_orientation_target(q)
plan = robot_commander.plan()
robot_commander.execute(plan) // besides: what is the difference to 'go()'  here?

and the resulting position is:

position:   
  x: 0.685057598278   
  y: -0.21755076457   
  z: 1.57268680334   
orientation:   
  x: -0.000313327718826  
  y: 0.000491862755421     
  z: 0.999999828845     
  w: 4.69705978272e-05

Which is ok when you only look at the orientation, but the position is off by more than 40cm.. I guess i could just save the joint states and let the robot move to them, but i want to know whats going on here? What am i missing?