How Radix-8 and Radix-2^3 are related
Radix-2^3 is a special class of radix-2 algorithms where the basic decomposition is based on radix-8 and the 8-point DFTs are later on decomposed into radix-2, leading to an algorithm based on radix-2 butterflies.

"Same" depends on what you mean and how you classify algorithms. In some sense, a valid way to implement a radix-8 butterfly is to decompose it into radix-2 butterflies. Still, using classic definitions, the size of the fundamental butterfly operation that is realized determines the radix, leading to that radix-8 and radix-2^3 are "different".