Any differences in scores I've seen/heard about are anecdotal, but of the few kids I know who've taken both, the SB-V tends to run a bit lower for FSIQ. I've generally heard that the WISC is better for verbal kids and the SB for mathy kids if you are looking for a higher score or to hit on the kid's strengths, but again I'm not sure if that is just anecdote.

Study Strategies for Accelerated Learners