Two different animals.
Plated bullets are most often associated with pistol bullets. The plating is very thin and usually applied by an electro-plating process. It's mainly to reduce lead fouling in pistol bores.
FMJ is just that. It's a much thicker actual jacket that is swaged onto a lead pellet in more conventional cup and core process bullet making.
The base of most FMJ bullets has an exposed lead bullet base. Plated bullets are completely encased in the plating metal.