Nope, you are correct about editions, MumofThree. You are describing the practical implications of the Flynn effect.

The bigger difference is between the WPPSI and the WISC. The WPPSI-IV and the WISC-IV do not have the same index structure, nor do they have nearly as much overlap in subtests as, say the WISC-IV and WAIS-IV. The WPPSI-IV is more like the newly-released WISC-V.

I'll try to answer in more detail later.

...pronounced like the long vowel and first letter of the alphabet...