I think there is a 10mm variation permitted at certain points when measuring with the hull templates. It would certainly be a challenge to build to the templates with stressed ply at home.

The carbon masts has to go trough a deflection test when measured, this is where the differences show up. They are not identical, but quite close. These data used to be available on the ITA website. We had quite a debacle on the topic at the time and I am not certain how much really came out of the change to carbon masts.