I’m assuming you’re talking about safety planes here?
If so, those are identifiers to determine when the robot should acknowledge the safety plane.
Normal - when the robot is in normal mode, the safety plane will prevent the robot from passing through the plane. If it passes through the plane, a safety violation occurs, and the robot goes into recovery mode.
Reduced - same as Normal, but now everything only applies while the robot is in Reduced mode.
Both - the plane and it’s violations are applied any time the robot arm is fully powered on.
Trigger Reduced Mode - when the robot passes through the plane, the robot will change from Normal to Reduced mode. There will be no safety violations triggered by passing through the plane.
You are correct on the difference. The only difference between a normal and reduced boundary is when the boundary applies to the robot.
Normal boundary - applies with Robot in normal mode only, and not during reduced mode.
Reduced boundary - applies with robot in reduced mode only, and not during normal mode.
Further information can be found in section “21.11.1 Modes” of the user manual.