Tapping is the operation of cutting internal threads in a hole with a cutting tool called a Tap. Special machine or gun taps are used with a tapping attachment when this operation is performed by power in a machine.
Threading may be defined as the operation of cutting external threads in a round rod with a cutting tool called a Die. To make threads we also can use turning operations on a turning machine which is also called thread cutting on turning or thread turning.
With milling machines we can produce thread on a round rod too which is called thread milling, and the tool is called a thread mill.