The bottom image has affect shadows turned on. There is a fake caustic ef-
fect but it’s nowhere near physically correct.
Note that the V-Ray light is a special light. Although it casts direct light just
like max lights do, they do
produce GI caustics (max
lights don’t!). Normally
only first bounce GI light
(like the light coming from
skylight and object lights
like our light box) produces GI caustics.