Is there any difference between tapping screw and threads made by taps ?
Difference is whether the accuracy is needed or not. Tapping screws are used in such application as the accuracy is not so much needed.They are used the rear lids of washing machines which are not opened or shut so often. Screws made by taps are for such usages as require precision and accuracy. They are used for Shinkansen railway and for aircrafts. One of their advantages is that they can be disassembled whenever is needed.