What is the difference between bread flour and all-purpose flour?
Bread flour (also known as strong flour) is higher in protein than regular all-purpose flour. Using it can lead to better gluten development, but it also creates a tougher dough.
And soft flour? Cake flour? Type 55 flour?
Soft flour is close to what is called cake flour in the United States. It is lower in protein and creates a softer, crumbly crumb. It doesn't tend to be strong enough for most bread recipes, though it is great for cakes and quick breads.
Type 55 flour, which is often used for French baguettes, is fairly close to American all-purpose flour.