I'm familiar with a normal distribution. That doesn't mean that there is a bigger difference between a 120 and a 130 vs. a 130 and 140.
Agreed. I'm a statistician and I have no idea what that means. There are fewer people with IQs in the range of 130 to 140 vs people in the range of 120 to 130. There may also be more qualitative differences in the experiences of people in those ranges as well.
I have 2 kids, both in AAP, both tested with the WISC for reasons having nothing to do with AAP. One has a FSIQ of 129 and the other of 146. I can tell you the 146 kid struggles a lot more in almost ALL ways than the 129 kid.