Baking powder is a special agent that increases lift in various bakery recipes, including; bread loaves, rolls, muffins and American pancakes. Borwick's baking powder is to be used in the exact amount given in the recipe you follow. Usually you'd use baking powder in plain flour.
Borwick's Bicarbonate of Soda (100g) It is similar to baking powder, but comes in a more basic form that requires "activation" via combining it with other ingredients such as buttermilk, vinegar or stout. The activation process releases carbon dioxide into the dough, forming bubbles that help the dough to rise