The main difference between bread flour and self-rising flour is the leavening agents. Self-rising flour already contains baking powder and salt, which helps your baked goods rise, whereas bread flour does not. This means you'll need to add your own leavening agents when using bread flour - no biggie, just a little extra work!
Now, you might be thinking, "But wait, can't I just use self-rising flour to make bread?" Well, technically, yes, you can, but the result might be a bit... unexpected. Self-rising flour can make your bread taste more like a quick bread or a biscuit, rather than a traditional loaf. Not bad, just different!