For Straight Lines the object has a starting position (or first point) - altering this value causes the whole object to move relative to the layout origin.
End Pt 2
Straight Lines have a second point, altering this, moves just that end of the line, altering its length as needed.
Line Angle
Straight Lines have an angle - this is the angle between the two points, altering this moves the ends so as to respect the Pivot control setting.
Length
The Length control can add to the start or end or both of a Line object depending on the setting of the Pivot control setting.
1.15.0