The difference in Opaque & Transparent beads deals with the core color only, not the clear that encases the color.
OPAQUE - when you look as the color side of the bead, in theory you would NOT be able to see a wire running through the hole. Frequently the opaque beads have a white core, but not always.
TRANSPARENT - when you look at the color side of the bead, in theory you would be able to see a wire running through the hole, although it is not normally seen in finished jewelry.