# Why is a Feistel network not a type of substitution-permutation network?

I understand what substitution-permutation networks look like. I understand what Feistel networks and Feistel-like networks look like. A Feistel network or a Feistel-like network features substitution and permutations, so why is it considered distinct from an SP-network?

• Your question is not clear. A Feistel network could contain an SPN in its $f$ function but that is distinctly different from SPN itself – sashank Apr 7 '15 at 16:53