I think the difference between 4 and 5 is two things:

1) Motivation/Intensity/Drive
and
2) Breadth

So I think a kid can't be a level 5 unless they have #1 in multiple areas. So a kid who performs at level 5 levels in only one area, is still only a level 4.

Again, I know level 5 people and there is an intensity to them that you definitely know when you see it.