Ultimately they all measure some form or combination of pressure, temperature or flow. As far as I know, all pressure sensors actually measure movement in response to pressure, whether it is the distortion of a crystal, stretching of a resistive wire, whatever. A transducer explicitly canverts one form of energy or force into another. A crystal that generates a voltage in response to strain would be one example. The deflection form of force is converted to electrical force.
Most sensors take raw data and 'condition' it to be suitable for some form of instrumentation.
A transducer explicitly canverts one form of energy or force into another. A crystal that generates a voltage in response to strain would be one example. The deflection form of force is converted to electrical force.