The second group believed in the supremacy of the Aryan race (whites for those in Rio Linda) while the first group did not.
Would a racist nation have sent their white sons to fight against other whites if it were a racist nation???
Revisionist works such as War Without Mercy: Race and Power in the Pacific War by John Dower (New York: Pantheon,1986) claim that white racism was a major reason that we went to war with Japan.