Workspace with active tool

Hi all,
I have noticed something unexpected in RobotStudio. I have defined a tool with origin coincident with tool 0, just I gave info about the mass and center of gravity. In rapid after synchronization I have:
PERS tooldata Vacuum := [TRUE, [0,0,0],[1,0,0,0]],[20,[0,0,77.5],[1,0,0,0],0,0,0]];

I thought that showing the workspace in RobotStudio with respect to the wrist or to the active tool should result in the same workspace since the 2 reference frames are coincident. Actually the workspace with the active tool is a bit bigger. Does anyone knows why this happens? I thought everything was related to TCP position and it is the same as tool0.