A Field Effect Transistor (FET) is a three-terminal Active semiconductor device, where the output current is controlled by an electric field generated by the input voltage.
The metal-oxide-semiconductor field-effect transistor (MOSFET, MOS-FET, or MOS FET) is a type of field-effect transistor (FET), most commonly fabricated by the controlled oxidation of silicon. It has an insulated gate, the voltage of which determines the conductivity of the device.
Every transistor and fet is analog.
The diode is a type of uncontrolled switch whereas the transistor is a controlled switch. The transistor is mainly classified into two types, i.e., the Bipolar junction transistor and Field Effecting Transistor. The BJT uses both the electrons and hole as a charge carrier, and the FET is a unipolar transistor.