Definition of the taps in this kit you will receive:
Plug Tap: Most common tap type, has a slight taper, generally between 3 and 6 threads.
Taper Tap: More pronounced taper, less aggressive than plug type taps, taper is generally between 8 and 12 threads.
Bottom Tap: Has a continuous cutting edge with very little taper, generally between 1 and 3 threads.
If you have any questions, please feel free to ask - we're always happy to help!