if you ignore the linear mode, they're better characterised as current-controlled diodes, because if they're off there's a leakage current and if they're on there's a forward-biased diode

a FET is more like a switch in that it Has Resistance if its on and has Open Loop Resistance if its off (and the energy you use to operate it is on the order of nanojoules, but thats beside the point i guess)