Here you see the Begins head, the TDK release and finally the TDKR release.
The most immediately noticeable difference is the devolving paint job done to the unmasked portion of his face. It's much more detailed and properly fleshtoned in the Begins figure. (which is funny, because that came out after the release of the DK version.) By the time we get to the Rises releases it's kind of just a peach blob on his face.
Not so apparent is the mold differences. On the Begins head, it's over all more rounded, and the ridges for the brow and and cheekbones are more prominent and extend farther.
My camera wouldn't pick it up, but the most telling detail that they're different sculpts, or at the very least different molds made from the same sculpt, is around the nose. If you look at the TDK head, there is a line, a horizontal mold seam, coming from the nose to where the face meets the vertical mold seam at the back of the head. This is on all releases that i have of the TDK figure (original, Rises, Bane two pack). This is completely absent on the Begins head.