A Healing preset can both Heal and Kill. The frequency is the most important variable. It is perfectly ok to use Healing presets for both Killing and Healing programs, because these presets are gentle on the body. Likewise, Killing presets can also be used for healing, but these generally put more stress on the body, so are not recommended for healing purposes.
Johann Stegmann, a leading researcher, found that a Healing preset had the killing ability of a Killing preset without exposing people to undue stress. So we recommend using a Healing preset for almost all applications. This makes treatments significantly more simple.
Presets alter the waveform, offset, duty cycle, and many other things. Killing presets use settings which make the signal stronger. Sometimes a stronger signal is not desirable, even if the function of a program is to kill. It may actually slow down the healing process.
Just as shouting does not make a voice clearer, more power does not necessarily make a frequency better.