The White Milliskin is smoother...and being lighter in weight, will stretch out to a smooth surface with less tension needed. less tension means less stretching open of the weave. A tighter weave will reflect more light. A smoother weave means more detail.
The Light Silver Milliskin is also to a small degree more reflective than the Silver Moleskin, though boht are pretty close to the same shade. Once again, the tighter weave will reflect more, and absorb less.
Silver under white serves to enhance contrast...while White over silver allows for the brightest possible Colors and most pristine Whites. Either Color alone has significant drawbacks. It's become apparent that only those with uber lumen output (...via a Short Throw, or high Lumen Pj...or both...) should consider using either the Silver Moleskin or the Light Silver Milliskin as a top layer, and if such is done, absolutely the Top should be backed with White Milliskin. In truth, unless directly comparing a Silver Milliskin Top surface with a White Milliskin Top surface, the Light Silver does in fact look very good! But put a White beside it / over it and the difference in the appearance of the White levels is striking. But that's how all comparisons between basic Grays and Whites turn out. For many, the greatly improved Black levels and deeper Color saturation of a Gray / Silver are worth the attenuation of Whites...to at least a reasonable degree. On the Flip...those who want the brightest possible image are often very biased toward losing any degree of such.
Using a White Milliskin Top Layer over a Light Silver Milliskin under-layment is the best possible blending of the two for most applications. That statement might be construed as being a "IMHO" but must also be qualified a bit more due to my having "Been there...Done that" as well.
Wanna get Lucky? Tell the Wifey to model the left over strips of "thin" white Spandex, a" as well.a Sheena style. Put 'em to good use. Posting Images is optional.