Self-drilling screws are easy to distinguish if you look at their point, which curves gently at the end and is shaped like a twist drill. They're often called Tek Screws, after the brand name that popularized them.
Self-drilling screws are also called tek screws. Its drill bit tips are numbered from #1 up to #5, indicating the length of the flute, which determines the metal thickness the screw can drill into. The bigger the number is, the thicker the metal a screw can go through.
The hex head self-drilling screws have three main types of drill points, Tek 3, Tek 4, and Tek 5. There’s also Tek 1 self-drilling hex head screw, whose point is also called reduced drill.