Is there a difference between baking flour and plain flour?

Plain flour is most likely all purpose flour. It will work just fine for bread, but bread flour is specifically blended for bread making. It has more gluten which is what forms the bubbles in bread and helps it rise better. Plain flour is milled, blended and produced slightly differently than that for bread flour. Bread flour is much more of a stronger flour, whilst plain white flour is not. Both flours (whilst bread flour being the best to use for bread), need raising agents, since the flours are heavy. The most commonly used agent is yeast, in small amounts depending on size of loaf. Better results are achieved with using bread flour. So if you want to make bread then best use bread flour for better results and much tastier well balanced bread.