New Roll Tap (NRT) and High Roll Tap (HRT) are both forming tap
While HRT is a rolled-finish tap with basic performance and is limited to sizes of M6 or less, NRT is a grinding-finished tap with a wide variety of tool base material , various coatings, application-specific specifications, and small diameter ~ large diameters, making it possible to meet a variety of machining needs.
Note that the recommended pilot hole diameter for each is slightly different.
However, HRT is now discontinued