I always hear that flour is one of those ingredients that varies a lot from country to country and that the variations can have a marked effect on the baking outcome- hard wheat versus soft wheat, higher or lower protein content, more or less gluten, inclusion of small amounts of cornstarch, etc.

Does anyone know what the specific differences are between US white/all purpose flour, and the standard Swiss Weissmehl from the supermarket? Beyond that, if one is using a recipe that assumes the use of American flour, are there any adjustments you'd recommend making in any circumstances? (Most of my baking has come out fine with just a straightforward substitution so far, but there's always room for improvement!)