Most consumers are totally confused when they try to compare one tens machine to another tens machine. The information may be spelled out, per FDA regulations, but that does not mean the customer understands or can compare electrotherapy devices. Often it behooves a manufacturer to keep the customer confused and make benefit statements, rather than disclose whether their machine is truly different or not.
The video below attempts to explain in layman terms what tens machines, functional electrical muscle stimulators, Infrex interferential machines, iontophoresis machines actually do and how to decipher the technical terms into everyday language.