[maxnoe]

It's the only difference in ingredients.

But the difference is a world apart.

The best example is rye bread, which won't develop a crumb without sour dough.

Concerning the fodmaps, it is the usually longer fermentation that reduces those.

[graeme]

Note that rye sourdough is still high fodmap. Found this out early on when I realized it still caused symptoms.

True wheat sourdough is hard to find too. Most bakeries put in yeast and label it sourdough.