on the left we have the image with the diffusion box(tent, light box, whatever you want to call it)
and on the right the one without.....
as I said in the earlier post the one on the left I'm also using a sheet of paper to fill in the shadow side to emphasize the effect of the box.
The things to notice between the two shots is the Highlights on his arm closest to the light source. Look at the difference in both the shape and the size of them (but as previously noted this will change and improve the bigger the box is, the one i'm using here is very small). Your angle will also matter on this, look at the images below where I'm at a slightly higher angle to get the entire set up the highlights are wider not just across his arm but on his chest as well, when photographing shiny objects this type of lighting is the way to go!
Also note the light edge transition from light to dark.
As well take note of the background, the diffused (box) lights up the background more evenly while the standard (or "hard light") creates more of a spot light effect.