Different test, but yes, that's generally correct.
With regard to splits within indices: they also suggest that interpretation at the index level is not going to capture the full range of a child's strengths and weaknesses.
For example, in older children, a split between verbal reasoning (Si) and verbal knowledge (Vo) favoring reasoning is not uncommon in learners with a history of early or on-going reading delays, because as one progresses through school, more and more high-level vocabulary comes from text, rather than one's oral language environment. The reasoning task is not quite as heavily weighted for reading vocabulary as (obviously) the vocabulary task is, and consequently is not as affected by prolonged lack of access to text. In the VSI, one of the tasks is quite motor-involved, and the other is not; children with motor deficits might be expected to have diverse performance along those lines. WMI is made up of an auditory memory task, and a visual memory task. One is also more symbolic, while the other is more concrete. Memory profiles can be quite diverse as well (there are whole tests designed to hone in on specific memory skills, far more comprehensive than these two subtests can be).
