A GF LightSphere, the D-I-Y version, or similar ('Tupperware') diffusors spread the flash gun's light not only to the front, but also to the sides and the rear of the flash gun. That light – 3/4 of the total output – is completely wasted if there is nothing to bounce it off of. A GF LightSphere, the D-I-Y version, or similar ('Tupperware') diffusors is/are therefore only (limited) effective in (en)close(d) quarters, but totally useless in 'open spaces' (more than 10 feet from possible reflecting walls/ceilings), where it will only cut heavily into your flash gun's light output and therefore cut your DoF down to a 1/4 or less...
This one is much more effective as it prevents wasting light to the rear and the sides of the flash gun. It effectively works as a portable softbox and makes much more efficient and effective use of your flash gun's output.