If you scale an obect with the model tool the object’s scale won’t change at all–it will remain at 1/1/1 while the object’s size will change in world units. If scale with the object tool it will change the scale and size in world units. If your scale is something other than 1/1/1 and you run reset system the scale will be reset back to 1/1/1, but the object’s size in world units will *not* change.