What are the differences between self-tapping and self-drilling screws, and which type is more suitable for a specific application?

Self-tapping screws have a sharp tip that can cut its own threads into the material, while self-drilling screws have a drill bit tip that can create a hole before threading. Self-tapping screws are better for softer materials like wood, while self-drilling screws are more suitable for harder materials like metal. Choose self-tapping screws for wood and self-drilling screws for metal for best results.