sure how you want this answered so ill put it in simple terms related to modern automotive.a sensor is a device that collects information and relay it to the computer for operational use. a switch is a device that controls a circuit of some type aka door locks, blinkers and windshield wipers. if that explanation isnt good enough then please leave a comment with a more specific question about them and i will answer it.

no a switch is on or off, a sensor is variable

Sometimes but that depends entirely on the application.

A sensor can have a variable output based on its application or it can have a fixed output. A sensor like a photoelectric eye that turns a light on when the ambient light drops below a certain level is really just a switch. The eye can be removed and replaced with a simple on/off switch. A sensor like a temperature sensor that controls a cooling fan can either send a signal to a computer that decides when to turn the fan on and off based on set parameters or it can control the electric fan or fan relay directly using a mechanical temperature switch, kind of like a basic home thermostat, this type of sensor can be replaced by a manual switch. A sensor like a crank shaft sensor can use a magnetic field to count teeth on the flywheel, this signal is then fed to the ECM and determines when to deliver spark to which cylinder and what the engine rpm is. This type of sensor cannot be replaced by a switch because it has a variable output. So, sometimes a sensor is really just an automated switch and sometimes a sensor is not a switch.

No