They are each dyed with three colors.
Childhood is fuchsia, yellow, and turquoise. Where the colors overlap bright secondary colors (orange, green, and purple) are formed. I try to make sure that each of the six resulting colors have equal billing in the resulting skein of yarn.
Primary Race is red, yellow, and blue. There is not much overlapping of the colors. A little, but not as much as Childhood. I was originally going to name this Teen Angst since it is a darker, harsher version of Childhood but when it came time to officially christen this one the primary colors just stood out so strongly. Especially once re-skeined.
Here are some side-by-side photos so that you can see the subtle (and not so subtle) differences between the two.