What are the differences between self-drilling screws and self-tapping screws, and which one is more suitable for my project?

Self-drilling screws have a drill bit tip that can penetrate metal without the need for pre-drilling, while self-tapping screws have a sharp thread that cuts into the material as it is screwed in. Self-drilling screws are typically more suitable for metal projects, as they create their own pilot hole, while self-tapping screws are better for softer materials like wood or plastic. Choose the type of screw based on the material you are working with in your project.