An Electrical towel warmer derives it heat from either being plugged in or hardwired.   Electrical towel warmers are much simpler to install than a hydronic towel warmer.   The advantage of a hardwired towel warmer is the wires are hidden.   Neither do you have to worry about installing near a outlet.   An electric towel warmer will utilize about the same amount of energy as one or two lightbulbs, depending on the model.  If you purchase  a plug in towel warmer in a matter of moments you can be enjoying the luxury of  a towel warmer.    An Hydronic towel warmer uses hot water or steam to heat the towel rails.  Hydronic uses the same principles as a radiator.