Electrical switches and dimmers control electrical loads in general, and lamps in particular. Electrical switches typically switch all kinds of loads but the application of dimmers is restricted to lamps.
Depending on the dimmer method only resistive incandescent or a broader range of inductive and reactive loads are dimmable. Wall outlet plug-in devices are installed very easily without any further electric knowledge by just plugging them into the wall outlet. Wall plug-in devices receive Z-Wave signals from controllers and switch their load accordingly.