I voted 4A shrinks more. I base this on my own hair. My curly hair (4A) shrinks to about 1/2 it's length. My hair with no curl pattern, just cotton-y and course (4B) does not shrink at all.
The front of my hair sticks up on end b/c it's straight, not coily. The kink causes some shrinkage but not anything that is noticeable. In it's natural state, my bangs appear to be the longest part of my hair, when in reality, it's the shortest.