There are some pretty solid explanations on the NFER website:
Non-Verbal: http://www.nfer.ac.uk/nfer/research/ass ... -tests.cfm
Verbal: http://www.nfer.ac.uk/nfer/research/ass ... -tests.cfm
I will see if I can dig up anything else for you, but my advice would be not to get too bogged down in this for the appeal. Panel members will know what the difference is, and if you can demonstrate that your daughter's greatest strengths lie in scientific and technical subjects, that should be enough to explain the difference in scores.
The key phrase in the NFER definition of VR is probably the second part of this: "the view of verbal reasoning tests as fixed measures of potential has declined and they are now better regarded as measures of reasoning which reflect a person’s educational experiences up to the time of testing."