Bread bought two hundred kilometres apart can differ completely in crust, crumb and keeping quality. The variables are technical, and regional styles survive because baking stayed local.
The flour is the starting difference
Wheat varieties differ in protein content and in how their gluten behaves, and the varieties grown in a region were selected for its climate and soil.
Milling then changes the result again, since the extraction rate determines how much bran and germ remain in the flour.
Higher extraction flours produce darker, denser, more flavoured loaves that keep longer, which is why upland and northern regions historically favoured them.
Fermentation time does most of the work
A dough left to ferment slowly develops acidity and complexity that a fast-risen dough cannot, because the flavour compounds take hours to form.
Bakeries working with a long fermentation must plan their day around it, which sets how many batches they can produce and what they can charge.
Where a naturally leavened starter is used instead of commercial yeast, the microbial population itself varies by bakery, which adds another layer of local character.
Water and salt vary more than expected
Hydration, the ratio of water to flour, determines whether a crumb is open and irregular or tight and even, and regional styles sit at different points on that scale.
Very wet doughs are harder to handle and require skill and equipment, which historically limited them to places where the style was established.
Salt levels differ by tradition and in some countries by regulation, and salt also slows fermentation, so the two variables interact rather than acting separately.
The oven shapes the crust
A masonry oven holding heat in its floor and walls delivers a different bake from a deck oven, particularly in how the crust sets.
Steam introduced early keeps the surface flexible so the loaf can expand, and how that steam is generated differs between oven types.
Wood-fired ovens also drop in temperature through a bake, which produces a sequence of different breads from one firing and shaped traditional baking schedules.
Why the differences survived
Bread does not travel well, so bakeries remained small and local long after other food production consolidated into larger operations.
A small bakery serves a defined area and answers to customers who have eaten that style their whole lives, which strongly resists standardisation.
Where industrial baking has taken over, the regional distinctions fade quickly, which is why they persist most visibly in areas that kept their village bakeries.