RX3 is the so-called home series, offers only the basic elements without any quirks, besides there is no descriptive field. It has a standard rail mount. How do you have a whole row of circuit breakers connected by a busbar, the so-called comb, then to replace one you have to unscrew the entire comb. The TX3 can be replaced individually with the comb fitted. Besides, the electrical parameters are probably comparable.
