Yes and no. The difference is fairly sizable, but your child is also quite young, at an age when there is a wide range of developmental curves. She is also, presumably, not in a great deal of systematic formal education yet, so there may be differences in the content and extent of her exposure to different aspects of academic knowledge.
The reporting of index scores is a bit nonstandard, though, especially when the psych is not concerned about LD. Why is the FSIQ an approximation, and not exactly that number? I assume the Nonverbal Index was reported because the Verbal Comprehension scores were so much lower, and the psych was trying to present a global score without including them. I speculate that only two of the five primary index scores was reported because of the widely divergent results within the Visual Spatial and Fluid Reasoning Indices. But that doesn't explain why Processing Speed is not reported, since those scores are consistent with each other.
But I digress.
With regard to the differences in test results, in addition to the high degree of variability in young children, which is probably the most important factor, you are also comparing two different tests. Based on the date of your previous eval, and I would imagine that the previous test was also the WPPSI-IV, just the lower age-level (2:6-3:11) of the same test. (Even if it was actually the previous edition, the discussion below applies, as the structure of the test on the WPPSI-III was similar, as regards verbal and nonverbal clusters.)
The Verbal Comprehension tasks at that level are not exactly the same as those at the upper level. One subtest is entirely different (Receptive Vocabulary), in that it uses visual supports, and requires only a pointing response to identify the meaning of a word presented by the examiner. The other subtest is nominally the same, but starts with picture items at the lower level, as compared to verbal only items at the upper level.
The Nonverbal tasks on the lower level consist only of the two Visual Spatial tasks also administered at the upper level (BD and OA), plus the two working memory tasks. (On the WPPSI-III, the nonverbal cluster is called Performance IQ, and consists solely of the VSI tasks.) If you look at her performance on those two subtests (i.e., the Visual Spatial Index, not reported here) I suspect it is not that different from the Visual Spatial Index obtained at age 3. The older age Nonverbal Index takes the stronger of her two VSI subtests, two Fluid Reasoning subtests that weren't previously administered, and one each of the WMI and PSI subtests.
So it isn't really a one-to-one comparison. The correct comparison is the lower preschool level VSI (likely what you describe as the earlier nonverbal measure) to the upper preschool/kindergarten level VSI (not reported).
