Stack vs. Axle sole height specs on pedals

I decided to switch my pedals from Speedplay Zeros to Look Keo. I am trying to figure out how much I need to adjust the saddle. Speedplay website says the Look’s have a “Stack height” of 17.1mm (vs Zero’s stack height of 11.5mm), but the Look website says the Keo has a “Axle-sole Height” of 15.7mm.

Is Stack Height different from Axle-sole height? It seems to me both terms should mean the same, if both are… then speedplay has wrong info listed for a competitive product