The Win8 Refresh/Reset was based on an image preloaded by the OEM, or installed as part of a Win8 install. If you reset your computer, you'd get all the bloatware back unless you clean installed (which replaces the image).

Win10 Refresh/Reset doesn't have such an image, and just reconstructs a fresh state as part of the process, but then runs a package that the OEM preloads on the computer after resetting.

This tool basically deletes that package so that when you reset, you get a fresh copy without any of that bloatware reinstalled.