Why is this in the Marketplace?
Many favor the older Rubik's 5x5x5 for speed solving compared to the new because the new get too loose and catch (even if they don't pop). They are far better out of the box for your the general public but have no life as a speed cube.
Of course these days almost anyone would prefer a V-Cube, but within the Rubik's line being able to determine this might help a purchasing decision.
I suppose it also fits well in Puzzle Collecting. I originally moved it out of General but perhaps I chose the wrong forum. Depending on why someone is asking, it could apply to either. I suppose since the introduction of the V-Cubes perhaps collecting is the more likely interest, and as such I think I'll move it again.
P.S. I don't know if there is any way to easily tell from the outside. On mine it is trivial to tell though, just pick it up by just touching the centers and shake it. If it rattles, it is probably the new version. Another method is to try to pop a piece. Not hard on the original, not easy (I have never done it for fear something would break) on the new version.