Difference between get_actual_tcp_po() and get_forward_kin()

Hi, guys, when I was using the robot script, Can be found in information website (Universal Robots - URScript: Move with respect to a custom feature/frame) Use get_forward_kin() to obtain the current pose of the robot, and find get_actual_tcp_pos() in scriptManual.pdf(https://s3-eu-west-1.amazonaws.com/ur-support-site/53318/scriptManual.pdf) to obtain the current pose of the robot.
So if I want to use pose_trans to make the robot move based on the toolset, which should I use?
Can you also describe the difference between these two functions? Because I couldn’t find a description for get_forward_kin().
Thank you, everybody.

Not totally clear what the difference really is, but I use get_actual_tcp_pose() pretty often to shift around relative to the Tool.