get_actual_joint_positions() returns a List variable, with length 6, containing the joint angles in radians. E.g. [0,1.57,1.57,0,1.57,0]. This is hence a List, and not a Pose.
Poses are denoted by a lower-case p in front of a list. Also, instead of joint angles, they contain Cartesian coordinate offsets from some coordinate system, respective in meters for translation, and radians for rotation. get_actual_tcp_pose() returns a pose, and should hence work just fine in the example pose_trans(pose1, pose2) above.
E.g. p[0.2, 0.1, 0.0, 0, 3.1415, 0]