The hash function "SHA-512/256" has different initial constants than "SHA-512", so it is not equivalent to truncating a "SHA-512" hash value. SHA-224 and SHA-3

The hash function "SHA-512/256" has different initial constants than "SHA-512", so it is not equivalent to truncating a "SHA-512" hash value. SHA-224 and SHA-384 are somewhat resistant to length-extension attacks because they output a truncated state. Yeah, the slash in the names are an unfortunate choice that hurts clarity.