So, the big difference between the WISC-IV and -V is that the PRI has been split into two indices, the Visual-Spatial and Fluid Reasoning Indices. There are also half-a-dozen supplementary indices that can be derived, including a Nonverbal Index. Quite a few ancillary subtests were added, looking at such areas as rapid naming and orthographic coding (or trying to, anyway). Some items have been updated, and minor modifications made to scoring/basal/ceiling rules, in the interest of streamlining testing. Supposedly, the floor and ceiling of the subtests have been strengthened, to improve utility for the extremes. The new core subtests largely come to the WISC from the WPPSI-IV or WAIS-IV.
